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Clinical outcomes and cost-effectiveness of superficial parotidectomy versus extracapsular dissection of the parotid gland: a single-centre retrospective study of 161 patients

  • R. Vanroose
    Correspondence
    Correspondence to: Department of Oral and Maxillofacial Surgery, ETZ Tilburg, Hilvarenbeekse Weg 60, 5022GC Tilburg, the Netherlands.
    Affiliations
    Department of Oral Health Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium

    Department of Oral and Maxillofacial Surgery, Sint-Elisabeth Hospital, Tilburg, the Netherlands
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  • J. Scheerlinck
    Affiliations
    Department of Oral and Maxillofacial Surgery, Sint-Elisabeth Hospital, Tilburg, the Netherlands
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  • R. Coopman
    Affiliations
    Department of Oral Health Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium

    Department of Plastic, Reconstructive and Aesthetic Surgery, Ghent University Hospital, Ghent, Belgium
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  • E. Nout
    Affiliations
    Department of Oral Health Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium

    Department of Oral and Maxillofacial Surgery, Sint-Elisabeth Hospital, Tilburg, the Netherlands
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Open AccessPublished:May 24, 2022DOI:https://doi.org/10.1016/j.ijom.2022.05.001

      Abstract

      Improvements in preoperative diagnostics and intraoperative techniques have made the surgical excision of benign parotid gland tumours less invasive. Extracapsular dissection (ECD) has become more popular in comparison to superficial parotidectomy (SP), the gold standard. Although clinical outcomes have been reported, reports on cost-effectiveness are limited. The aim of this retrospective study was to analyse the surgical outcomes and cost-effectiveness of ECD versus SP in benign parotid tumour surgery. A retrospective cohort of 161 patients treated between 2012 and 2020 was collected. Data concerning demographics, clinical outcomes, and cost-efficiency were recorded. Analysis of the 161 unilateral parotidectomy cases (59 SP, 102 ECD) showed a significantly longer operation time, anaesthesia time, and length of stay for SP patients (all P < 0.001). Regarding postoperative complications, transient facial nerve weakness (P < 0.001) and haematoma formation (P = 0.016) were more prevalent in the SP patients. The frequency of positive margins was lower for SP (P = 0.037). No case of recurrence was identified with either technique. ECD showed excellent clinical outcomes as well as a reduction in complications when compared to SP. ECD is a viable alternative for superficial benign parotid gland tumours after thorough preoperative clinical, pathological, and radiological examination. The reduction in operation, anaesthesia, and hospitalization times with ECD is likely to result in a gain in cost-effectiveness.

      Keywords

      Abbreviations:

      ECD (Extracapsular dissection), SP (Superficial parotidectomy), SGT (Salivary gland tumour), FNAC (Fine needle aspiration cytology), MRI (Magnetic resonance imaging)

      Introduction

      The parotid is the largest of the three major salivary glands.
      • Kochhar A.
      • Larian B.
      • Azizzadeh B.
      Facial nerve and parotid gland anatomy.
      Tumours in the salivary glands account for 0.2–1% of all cancers and 3% of all head and neck tumours. Eighty percent of salivary gland tumours (SGTs) are found in the parotid, of which 80% are benign.
      • Liu C.C.
      • Jethwa A.R.
      • Khariwala S.S.
      • Johnson J.
      • Shin J.J.
      Sensitivity, specificity, and posttest probability of parotid fine-needle aspiration: a systematic review and meta-analysis.
      • Dell’aversana Orabona G.
      • Salzano G.
      • Petrocelli M.
      • Iaconetta G.
      • Califano L.
      Reconstructive techniques of the parotid region.
      • Johns M.E.
      • Goldsmith M.M.
      Incidence, diagnosis, and classification of salivary gland tumors. Part 1.
      Furthermore, 90% of the benign parotid tumours are located in the superficial lobe, due to the fact that 80% of the parotid parenchyma is found lateral to the facial nerve.
      • Witt R.L.
      • Iro H.
      • McGurk M.
      The role of extracapsular dissection for benign parotid tumors.
      The fourth edition of the World Health Organization (WHO) Classification of Head and Neck Tumours (current version, 2017) includes 11 types of benign epithelial SGTs, of which pleomorphic adenoma is the most common, accounting for 65% of benign tumours; the second most common is Warthin tumour accounting for 25%.
      Historically, intracapsular enucleation (SGT removal within its capsule) resulted in unacceptable recurrence rates of up to 45%. Therefore, new surgical techniques were developed to surgically remove benign SGTs of the parotid.
      • Witt R.L.
      • Iro H.
      • McGurk M.
      The role of extracapsular dissection for benign parotid tumors.
      • Klintworth N.
      • Zenk J.
      • Koch M.
      • Iro H.
      Postoperative complications after extracapsular dissection of benign parotid lesions with particular reference to facial nerve function.
      • Barzan L.
      • Pin M.
      Extra-capsular dissection in benign parotid tumors.
      These include the superficial parotidectomy (SP), which involves complete removal of the superficial lobe of the parotid gland with facial nerve dissection, and the total parotidectomy, which involves complete removal of the superficial and deep lobes of the parotid gland with facial nerve dissection or transection. However, facial nerve dissection is associated with two important postoperative complications: temporary/permanent paresis/paralysis of the facial nerve and/or the development of Frey syndrome.
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      Intraoperative facial nerve monitoring and optical magnification, in addition to better preoperative diagnosis (ultrasound, fine needle aspiration cytology (FNAC), computed tomography, magnetic resonance imaging (MRI)) have enabled the surgeon to perform surgery in the parotid region more safely. These developments have allowed the scale of benign SGT surgery to be reduced from SP to extracapsular dissection (ECD), in which the SGT is removed with a margin of healthy salivary gland tissue, in an attempt to reduce postoperative complications.
      • Witt R.L.
      • Iro H.
      • McGurk M.
      The role of extracapsular dissection for benign parotid tumors.
      SP is still considered the gold standard for the removal of benign parotid tumours,
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      • Brennan P.A.
      • Ammar M.
      • Matharu J.
      Contemporary management of benign parotid tumours—the increasing evidence for extracapsular dissection.
      but ECD has been proposed as an alternative.
      • Witt R.L.
      • Iro H.
      • McGurk M.
      The role of extracapsular dissection for benign parotid tumors.
      • Klintworth N.
      • Zenk J.
      • Koch M.
      • Iro H.
      Postoperative complications after extracapsular dissection of benign parotid lesions with particular reference to facial nerve function.
      • Iro H.
      • Zenk J.
      Role of extracapsular dissection in surgical management of benign parotid tumors.
      A meta-analysis by Albergotti et al.
      • Albergotti W.G.
      • Nguyen S.A.
      • Zenk J.
      • Gillespie M.B.
      Extracapsular dissection for benign parotid tumors: a meta-analysis.
      reported less frequent facial nerve weakness and Frey syndrome and a recurrence rate similar to SP for ECD. However, the ECD cases appeared to have favourable characteristics, such as being singular, mobile, small (≤2.5–4 cm), and positioned far from the nerve and in the lateral and lower lobes, as illustrated in Fig. 1.
      • McGurk M.
      • Thomas B.L.
      • Renehan A.G.
      Extracapsular dissection for clinically benign parotid lumps: reduced morbidity without oncological compromise.
      • Deschler D.G.
      Extracapsular dissection of benign parotid tumors.
      Foresta et al.
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      reported ECD as a viable option for benign lesions (≤4 cm) in the superficial lobe without nerve involvement, which was reiterated by Xie et al..
      • Xie S.
      • Wang K.
      • Xu H.
      • Hua R.X.
      • Li T.Z.
      • Shan X.F.
      • Cai Z.G.
      PRISMA—extracapsular dissection versus superficial parotidectomy in treatment of benign parotid tumors: evidence from 3194 patients.
      There is still a lot of controversy regarding the criteria by which to choose either ECD or SP, and there is a noticeable gap in the literature concerning cost-effectiveness comparisons between the two treatment modalities. Kato et al.
      • Kato M.G.
      • Erkul E.
      • Nguyen S.A.
      • Day T.A.
      • Hornig J.D.
      • Lentsch E.J.
      • Gillespie M.B.
      Extracapsular dissection vs superficial parotidectomy of benign parotid lesions: surgical outcomes and cost-effectiveness analysis.
      described favourable cost-effectiveness for ECD compared to SP for benign parotid tumours, although they stated that studies with a longer follow-up and larger populations were needed to determine whether the advantages would be maintained over time.
      Fig. 1
      Fig. 1(A) Ideal case for extracapsular dissection due to the superficial location and small size of the tumour, far from the facial nerve; axial view. (B) Coronal view of the tumour in Fig. 1A, ideal for extracapsular dissection due to the location in the posterior lower lobe. (C) Ideal case for superficial parotidectomy due to the deeper location and larger size; axial view. (D) Coronal view of the tumour in Fig. 1C.
      The aim of this retrospective study was to analyse the surgical outcomes and cost-effectiveness of ECD versus SP in benign parotid tumour surgery.

      Materials and methods

      A retrospective evaluation covering the period 2012–2020 was performed in the Elisabeth-TweeSteden Ziekenhuis (Tilburg, The Netherlands). Inclusion criteria were patients who had undergone parotid surgery by ECD or SP surgical technique, who had preoperative FNAC and postoperative pathology reports available, and who had at least 1 year of clinical follow-up. Patients were excluded if they had primary malignant SGTs, secondary/metastatic malignancies, SGTs originating from the deep parotid lobe, had undergone revision surgery, or if a total parotidectomy was performed.
      The preoperative evaluation included a clinical examination for mobility and firmness of the SGT. Furthermore, pain and facial nerve paresis were clinically investigated. Following the initial clinical investigation, ultrasound-guided FNAC and MRI were conducted to exclude signs of malignancy. All parotid surgeries were performed under general anaesthesia with operator-worn loupe magnification and facial nerve monitoring. The SP was performed by dissecting the plane of the facial nerve antegrade and removing all of the parotid mass above. The ECD was performed without planned exposure or dissection of the facial nerve branches. Instead, the tumour was removed along with a 2–3-mm rim of healthy tissue. Daily evaluation was performed during the hospital stay until discharge. Afterwards, a personalized follow-up schedule was implemented, which was adjusted according to the histopathological findings, surgical complications, and tumour type. Facial nerve function was evaluated during follow-up consultations; possible gustatory sweating was only investigated after 6–12 months. Postoperative radiotherapy was not performed for benign lesions.
      Sociodemographic characteristics, surgical modality, length of the follow-up period, tumour type and location, and tumour recurrence data were extracted. Margins were defined as positive if the inked surface reached the resection margin in the histopathological analysis, or if tumour spill, capsule rupture, capsule perforation, or an incomplete capsule was reported during the surgery. Intraoperative events of prognostic significance, including sacrifice of a nerve, tumour spillage, etc., were also collected.
      Cost-efficiency was assessed by secondary endpoints including the durations of surgery, anaesthesia, and hospitalization and the occurrence of postoperative complications. Due to the heterogeneity of the retrospective data, an estimate of the real cost as the primary endpoint was not feasible. The following definitions were used: operating time was the time from first incision to wound closure, anaesthesia time was the time from induction to extubation, and length of stay was the number of days in hospital.
      The study was approved by the METC Brabant Ethics Committee.

      Statistical analysis

      The statistical analysis was performed on the anonymized data using IBM SPSS Statistics version 28.0 (IBM Corp., Armonk, NY, USA). Categorical variables were presented as frequencies, percentages, and/or range; numerical variables were presented as the mean± standard deviation. Values were displayed in their respective tables. The normality of the data distribution for continuous variables was determined using a combination of the Kolmogorov–Smirnov test, skewness, kurtosis, and a visual examination of the distribution. Comparisons between continuous variables were done using the independent t-test (in the case of a normal distribution) or Mann–Whitney U-test (non-normal distribution). The categorical variables were coded using a variable dependent numerical coding system. For the categorical variables, comparisons were performed with Fisher’s exact test or the Pearson χ2 test. Statistical significance was considered with a P-value lower than 0.05. A line graph was drawn to depict the number of cases of each surgery type (ECD and SP) performed per year.

      Results

      A total of 161 parotidectomies met the inclusion criteria: 102 were performed by ECD (63.4%) and 59 by SP (36.6%) technique. There was a relative increase in the frequency of ECD during the study period (Fig. 2).
      Fig. 2
      Fig. 2Increase in relative frequency of extracapsular dissection (ECD) compared to superficial parotidectomy (SP) over time.
      The sex distribution differed significantly between the two groups (P = 0.033), with male patients more frequently undergoing SP. There was no significant difference in median age at surgery, smoking status, or lesion side between the groups (Table 1). Lesion size was found to be significantly larger (P = 0.007) and the duration of follow-up significantly longer (P = 0.036) in the SP group. The 5-year disease-specific survival was 100%. Pleomorphic adenoma was the most common lesion type, followed by Warthin tumour; other lesions were less common (Table 1). The frequency of positive margin status was significantly higher in the ECD group (P = 0.037); 24.5% of ECD cases had positive margins compared to 10.2% of SP cases.
      Table 1Demographic factors and features of the lesion in the extracapsular dissection (ECD) and superficial parotidectomy (SP) groups.
      ECD (n = 102) n (%)SP (n = 59) n (%)P-value
      Age at surgery (years), mean (range)57 (22–83)58 (23–81)0.714
      Independent t-test.
      Sex0.033
      Pearson χ2 test.
      Male51 (50)40 (67.8)
      Female51 (50)19 (32.2)
      Lesion side0.744
      Pearson χ2 test.
      Right54 (52.9)29 (49.2)
      Left48 (47.1)30 (50.8)
      Smoking0.8
      Pearson χ2 test.
      Current39 (38.2)25 (42.4)
      Former17 (16.7)10 (16.9)
      Histopathological diagnosis
      Pleomorphic adenoma52 (51.0)27 (45.8)
      Warthin tumour41 (40.2)22 (37.3)
      Myoepithelioma1 (1.0)4 (6.8)
      Basal cell adenoma1 (1.0)1 (1.7)
      Cystadenoma0 (0)2 (3.4)
      Lymphadenoma0 (0)1 (1.7)
      Lymphangioma1 (1.0)0 (0)
      Lympho-epithelial cyst2 (2.0)2 (3.4)
      Spindle cell lipoma1 (1.0)0 (0)
      Ductal salivary cyst1 (1.0)0 (0)
      Retention cyst1 (1.0)0 (0)
      Reactive lymph node1 (1.0)0 (0)
      Lesion size (cm3), mean (range)52 (1.4–380)76 (3.4–390)0.007
      Mann–Whitney U-test.
      Margin status0.037
      Pearson χ2 test.
      Positive25 (24.5)6 (10.2)
      Negative77 (75.5)53 (89.8)
      Follow-up (years), mean (range)4.19 (1–9)4.98 (1–9)0.036
      Independent t-test.
      a Independent t-test.
      b Pearson χ2 test.
      c Mann–Whitney U-test.
      Table 2 shows the comparison of reported intraoperative events between the ECD and SP groups. In 30.4% of ECD cases, the facial nerve was exposed due to proximity to the tumour; the nerve was left intact in these cases. The facial nerve was transected in two cases, both in the SP group. A statistically significant difference in greater auricular nerve transection was found, due to the method of surgery in the SP group, whereby the greater auricular nerve is transected after incision.
      Table 2Intraoperative events.
      ECD (n = 102) n (%)SP (n = 59) n (%)P-value
      Greater auricular nerve transected9 (8.8)59 (100)< 0.001a
      Facial nerve branch transected0 (0)2 (3.4)0.133b
      Facial nerve branch exposed31 (30.4)59 (100)< 0.001a
      Retromandibular vein sacrificed1 (1.0)2 (3.4)0.555b
      ECD, extracapsular dissection; SP, superficial parotidectomy. aPearson χ2 test. bFisher’s exact test.
      The preoperative FNAC diagnosis was confirmed by the final pathological diagnosis in 79.5% of the cases, as shown in Table 3. Preoperative FNAC was inconclusive in 16 cases. Four cases of cystic lesions were suspected, and one reactive lymph node. Four cases were suspected to be pleomorphic adenoma and two cases to be Warthin tumour, but could not be definitively identified.
      Table 3Comparison between preoperative FNAC and final pathology.
      FNAC pathologyNumber (%)Final pathologyNumber (%)
      Pleomorphic adenoma75 (46.6)Pleomorphic adenoma79 (49.1)
      Warthin tumour55 (34.2)Warthin tumour63 (39.1)
      Likely pleomorphic adenoma4 (2.5)Myoepithelioma5 (3.1)
      Likely Warthin tumour2 (1.2)Basal cell adenoma2 (1.2)
      Basal cell adenoma2 (1.2)Cystadenoma2 (1.2)
      Myoepithelioma1 (0.6)Lymphadenoma1 (0.6)
      Spindle cell lipoma1 (0.6)Lymphangioma1 (0.6)
      Cystic lesion4 (2.5)Lympho-epithelial cyst4 (2.5)
      Reactive lymph node1 (0.6)Spindle cell lipoma1 (0.6)
      Classification not possible16 (10)Ductal salivary cyst1 (0.6)
      Retention cyst1 (0.6)
      Reactive lymph node1 (0.6)
      FNAC, fine needle aspiration cytology.
      Concerning the operation time, anaesthesia time, and length of hospital stay, statistically significant differences were found between the two procedures, as shown in Table 4. The operation time was found to be significantly shorter in the ECD group (P < 0.001). This also translated into a substantially shorter anaesthesia time (P < 0.001). The mean operation time in the ECD group was 69 ± 27 min, while this was 140 ± 23 min in the SP group. The anaesthesia time was 98 ± 28 min in the ECD group and 172 ± 27 min in the SP group. After the operation, patients in the ECD group were found to stay considerably shorter in the hospital (P < 0.001): a mean 0.7 ± 0.5 days, compared to 1.2 ± 0.5 days in the SP group.
      Table 4Cost-effectiveness characteristics.
      ECD Mean± SDSP Mean± SDP-value
      Operation time (min)69 ± 27140 ± 23< 0.001
      Mann–Whitney U-test.
      Anaesthesia time (min)98 ± 28172 ± 27< 0.001
      Mann–Whitney U-test.
      Length of stay (days)0.7 ± 0.51.2 ± 0.5< 0.001
      Mann–Whitney U-test.
      ECD, extracapsular dissection; SP, superficial parotidectomy; SD, standard deviation.
      a Mann–Whitney U-test.
      The SP and ECD complication rates were comparable in all categories, except for facial nerve palsy (P < 0.001), temporary facial nerve palsy (P < 0.001), and haematoma formation (P = 0.016), which were more prevalent following SP (Table 5). Sixteen (27.1%) cases of temporary facial nerve weakness were reported in the SP group and four (3.9%) in the ECD group. Haematoma formation was present in nine (15.3%) SP cases and four (3.9%) ECD cases. No statistically significant difference in permanent facial nerve weakness was found (P = 0.133).
      Table 5Postoperative complication rates.
      ECD (n = 102) n (%)SP (n = 59) n (%)P-value
      Frey syndrome (gustatory sweating)1 (1.0)3 (5.1)0.140
      Fisher’s exact test.
      Facial nerve palsy<0.001
      Fisher’s exact test.
      Temporary4 (3.9)16 (27.1)< 0.001
      Pearson χ2 test.
      Permanent0 (0)2 (3.4)0.133
      Fisher’s exact test.
      Dysesthesia of the greater auricular nerve0.214
      Fisher’s exact test.
      Temporary4 (3.9)1 (1.7)0.653
      Fisher’s exact test.
      Permanent5 (4.9)7 (12)0.125
      Fisher’s exact test.
      Seroma formation0 (0)2 (3.4)0.133
      Fisher’s exact test.
      Sialocele formation2 (2.0)1 (1.7)1
      Fisher’s exact test.
      Salivary fistula formation1 (1.0)3 (5.1)0.140
      Fisher’s exact test.
      Haematoma4 (3.9)9 (15.3)0.016
      Fisher’s exact test.
      Infection1 (1.0)2 (3.4)0.555
      Fisher’s exact test.
      ECD, extracapsular dissection; SP, superficial parotidectomy.
      a Fisher’s exact test.
      b Pearson χ2 test.

      Discussion

      In this study, significant differences were found between the SP and ECD groups in operation, anaesthesia, and hospitalization times. The mean operation time was significantly shorter in the ECD group; the longer surgery time in the SP group can be attributed to the time required for facial nerve identification. As a consequence, the mean anaesthesia time was also significantly reduced in the ECD group. Postoperatively the ECD group had a shorter hospital stay, with most patients in this group discharged on the same day with a drain in situ. They were seen later at an outpatient evaluation to remove the drain.
      Kato et al.
      • Kato M.G.
      • Erkul E.
      • Nguyen S.A.
      • Day T.A.
      • Hornig J.D.
      • Lentsch E.J.
      • Gillespie M.B.
      Extracapsular dissection vs superficial parotidectomy of benign parotid lesions: surgical outcomes and cost-effectiveness analysis.
      reported mean operation and anaesthesia times of 83 min and 148 min, respectively, in their ECD patient group and 139 min and 213 min, respectively, in their SP patient group; the differences between the two groups were statistically significant. A significant difference in length of hospitalization was also reported in their study: 0.5 days for ECD patients compared to 1.3 days for SP patients. In another study, Barzan and Pin
      • Barzan L.
      • Pin M.
      Extra-capsular dissection in benign parotid tumors.
      reported a mean operation time of 60 min for ECD and 150 min for SP. These results are in line with the results found in the present study and indicate that SP surgery takes approximately double the time of ECD surgery. Therefore, the possibility of performing two ECD procedures in the time of one SP arises. A shorter hospitalization and procedure are likely to result in lower health care costs for the patient and society.
      • Kato M.G.
      • Erkul E.
      • Nguyen S.A.
      • Day T.A.
      • Hornig J.D.
      • Lentsch E.J.
      • Gillespie M.B.
      Extracapsular dissection vs superficial parotidectomy of benign parotid lesions: surgical outcomes and cost-effectiveness analysis.
      The real cost of total benign parotid gland tumour surgery as a primary endpoint is almost impossible to determine. No literature was found on this topic. Further studies with a more economic focus will be needed to express the cost-efficiency in real monetary terms.
      Transient facial nerve palsy occurred in 27.1% of the SP cases and only 3.9% of the ECD cases (P < 0.001) in this study. This is comparable to the results of studies in the current literature, which have reported lower rates of transient and permanent facial nerve palsy with the ECD technique as well.
      • Barzan L.
      • Pin M.
      Extra-capsular dissection in benign parotid tumors.
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      • Xie S.
      • Wang K.
      • Xu H.
      • Hua R.X.
      • Li T.Z.
      • Shan X.F.
      • Cai Z.G.
      PRISMA—extracapsular dissection versus superficial parotidectomy in treatment of benign parotid tumors: evidence from 3194 patients.
      • Dell’Aversana Orabona G.
      • Bonavolonta P.
      • Iaconetta G.
      • Forte R.
      • Califano L.
      Surgical management of benign tumors of the parotid gland: extracapsular dissection versus superficial parotidectomy—our experience in 232 cases.
      In the meta-analysis by Xie et al.
      • Xie S.
      • Wang K.
      • Xu H.
      • Hua R.X.
      • Li T.Z.
      • Shan X.F.
      • Cai Z.G.
      PRISMA—extracapsular dissection versus superficial parotidectomy in treatment of benign parotid tumors: evidence from 3194 patients.
      and study by Mantsopoulos et al.,
      • Mantsopoulos K.
      • Koch M.
      • Klintworth N.
      • Zenk J.
      • Iro H.
      Evolution and changing trends in surgery for benign parotid tumors.
      Frey syndrome was reported to be significantly less prevalent after ECD. In the present study, Frey syndrome occurred in one (1.0%) ECD case and three (5.1%) SP cases, with no significant difference between the groups (P = 0.140), due to small numbers. Haematoma formation occurred more in the SP procedure than in ECD (P = 0.016). The reported complications can adversely affect quality of life, which shows the benefit of ECD due to the lower incidence of complications. Quality of life should be considered in comparisons between the two surgical modalities.
      • Ciuman R.R.
      • Oels W.
      • Jaussi R.
      • Dost P.
      Outcome, general, and symptom-specific quality of life after various types of parotid resection.
      No cases of recurrence were identified in this study, probably due to the limited follow-up. Martin et al.
      • Martin H.
      • Jayasinghe J.
      • Lowe T.
      Superficial parotidectomy versus extracapsular dissection: literature review and search for a gold standard technique.
      stated that due to the clinical nature of benign lesions, a follow-up time of at least 10 years is necessary to reliably evaluate the recurrence rate; this was not achieved in the present study. However, ECD has only recently been introduced at Elisabeth-TweeSteden Ziekenhuis to treat benign parotid lesions, although the relative share of ECD is increasing. Brennan et al.
      • Brennan P.A.
      • Ammar M.
      • Matharu J.
      Contemporary management of benign parotid tumours—the increasing evidence for extracapsular dissection.
      and Mantsopoulos et al.
      • Mantsopoulos K.
      • Scherl C.
      • Iro H.
      Investigation of arguments against properly indicated extracapsular dissection in the parotid gland.
      showed similar trends.
      In the literature, recurrence has been reported to occur up to 20 years postoperative, with varying recurrence rates and significance for ECD and SP.
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      • Albergotti W.G.
      • Nguyen S.A.
      • Zenk J.
      • Gillespie M.B.
      Extracapsular dissection for benign parotid tumors: a meta-analysis.
      • Xie S.
      • Wang K.
      • Xu H.
      • Hua R.X.
      • Li T.Z.
      • Shan X.F.
      • Cai Z.G.
      PRISMA—extracapsular dissection versus superficial parotidectomy in treatment of benign parotid tumors: evidence from 3194 patients.
      • Martin H.
      • Jayasinghe J.
      • Lowe T.
      Superficial parotidectomy versus extracapsular dissection: literature review and search for a gold standard technique.
      • Kanatas A.
      • Ho M.W.S.
      • Mücke T.
      Current thinking about the management of recurrent pleomorphic adenoma of the parotid: a structured review.
      • Bradley P.J.
      The recurrent pleomorphic adenoma conundrum.
      Foresta et al.
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      reported a higher recurrence rate in their SP group: 2.3 cases per 1000 person-years for SP compared to 0.2 cases per 1000 person-years in the ECD group. A recent meta-analysis by Martin et al.
      • Martin H.
      • Jayasinghe J.
      • Lowe T.
      Superficial parotidectomy versus extracapsular dissection: literature review and search for a gold standard technique.
      also reported a higher recurrence rate in the SP group. However, in these meta-analyses, ECD was used for relatively smaller parotid gland tumours compared to SP, resulting in a selection bias, which was also found in the present study, and could be a reason for the higher recurrence rate for SP described in the studies above. As a result of the inherent differences between the two procedures, ECD might be assumed to have narrower margins due to the dissection close to the capsule.
      • Barzan L.
      • Pin M.
      Extra-capsular dissection in benign parotid tumors.
      • Martin H.
      • Jayasinghe J.
      • Lowe T.
      Superficial parotidectomy versus extracapsular dissection: literature review and search for a gold standard technique.
      However, this disadvantage is present in a large part of SP cases too, due to the close location of the tumour against the nerve caused by the size of the tumour, thus necessitating a dissection step.
      • Barzan L.
      • Pin M.
      Extra-capsular dissection in benign parotid tumors.
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      Consequently, early removal is essential to prevent the need for the extra dissection step with higher chances of recurrence in SP. This way a cuff of healthy tissue is preserved, which prevents capsule rupture and potential spillage of the tumour contents – two of the reported risk factors for recurrence.
      • Foresta E.
      • Torroni A.
      • Di Nardo F.
      • de Waure C.
      • Poscia A.
      • Gasparini G.
      • Marianetti T.M.
      • Pelo S.
      Pleomorphic adenoma and benign parotid tumors: extracapsular dissection vs superficial parotidectomy—review of literature and meta-analysis.
      • Albergotti W.G.
      • Nguyen S.A.
      • Zenk J.
      • Gillespie M.B.
      Extracapsular dissection for benign parotid tumors: a meta-analysis.
      • Deschler D.G.
      Extracapsular dissection of benign parotid tumors.
      • Witt R.L.
      The significance of the margin in parotid surgery for pleomorphic adenoma.
      A barrier of healthy tissue also assists in less pseudopodia and tumour satellites being left behind.
      • Deschler D.G.
      Extracapsular dissection of benign parotid tumors.
      In ECD, no common guideline exists regarding the required thickness of tissue left around the tumour, with different thicknesses being reported by different authors.
      • Klintworth N.
      • Zenk J.
      • Koch M.
      • Iro H.
      Postoperative complications after extracapsular dissection of benign parotid lesions with particular reference to facial nerve function.
      • Deschler D.G.
      Extracapsular dissection of benign parotid tumors.
      • Dell’Aversana Orabona G.
      • Bonavolonta P.
      • Iaconetta G.
      • Forte R.
      • Califano L.
      Surgical management of benign tumors of the parotid gland: extracapsular dissection versus superficial parotidectomy—our experience in 232 cases.
      Despite the aforementioned advantages with respect to the ECD procedure, not all cases can be treated with this technique. Location plays an important role, with tumours of any size in the posterior lower lobe being favourable for removal by ECD. Pre-auricular lesions favour SP due to the closer location to the facial nerve trunk. Moreover, tumours with an intrinsic higher chance of recurrence and tumours localized in the deeper lobe of the parotid gland are removed with SP or total parotidectomy, resulting in selection bias.
      • Iro H.
      • Zenk J.
      Role of extracapsular dissection in surgical management of benign parotid tumors.
      • Deschler D.G.
      Extracapsular dissection of benign parotid tumors.
      Secondary ECD is primarily indicated for benign tumours, but potential false-negative preoperative assessment should be considered.
      • Deschler D.G.
      Extracapsular dissection of benign parotid tumors.
      A strict diagnostic protocol is necessary to discriminate between benign and malignant tumours; a combination of ultrasound-guided FNAC, clinical examination (benign SGTs usually do not affect the facial nerve and are almost always freely mobile), and MRI should be used.
      • Brennan P.A.
      • Ammar M.
      • Matharu J.
      Contemporary management of benign parotid tumours—the increasing evidence for extracapsular dissection.
      • Dell’Aversana Orabona G.
      • Bonavolonta P.
      • Iaconetta G.
      • Forte R.
      • Califano L.
      Surgical management of benign tumors of the parotid gland: extracapsular dissection versus superficial parotidectomy—our experience in 232 cases.
      A recent meta-analysis by Liu et al.
      • Liu C.C.
      • Jethwa A.R.
      • Khariwala S.S.
      • Johnson J.
      • Shin J.J.
      Sensitivity, specificity, and posttest probability of parotid fine-needle aspiration: a systematic review and meta-analysis.
      showed FNAC to have a sensitivity of 88% and specificity of 99.5% for discriminating between benign and malignant parotid tumours, with better results when ultrasound-guided. The Milan classification is a new tool to grade the degree of malignant potential of FNAC material from parotid tumours and is useful for determining the treatment protocol; a score of ≥ 5 represents a malignant lesion. This classification system was not applied in the cases included in the present study, but its more broad use in clinical practice and reporting of results in the literature is recommended.
      • Baloch Z.W.
      • Faquin W.C.
      • Layfield L.J.
      Is it time to develop a tiered classification scheme for salivary gland fine-needle aspiration specimens?.
      The Milan classification has been implemented at Elisabeth-TweeSteden Ziekenhuis since 2018, with cases at risk of malignancy expedited for surgery.
      In the present study, FNAC provided a correct final diagnosis in 79.5% of cases; no definitive diagnosis could be made in 20.5%. Therefore the situation arises where a tumour is preoperatively believed to be benign based on clinical (mobility, unilocularity, location, depth) and radiographic (well-defined margins, no enlarged lymph nodes) characteristics, but turns out to be malignant on postoperative histopathological analysis. If the course of the disease was shown to be negatively altered after performing ECD on those malignant lesions masquerading as benign, the widespread use of the new treatment method would be limited. An alternative to FNAC is ultrasound-guided true core biopsy. A histological tissue sample may provide more diagnostic certainty than an aspirate obtained by FNAC. Mantsopoulos et al.
      • Mantsopoulos K.
      • Velegrakis S.
      • Iro H.
      Unexpected detection of parotid gland malignancy during primary extracapsular dissection.
      described no adverse effect on survival or postoperative quality of life in those cases where ECD was performed due to a false-negative preoperative report. Furthermore, the surgeon must be able to deviate from a planned ECD and switch to more invasive/traditional surgery if signs of malignancy are detected.
      • Iro H.
      • Zenk J.
      Role of extracapsular dissection in surgical management of benign parotid tumors.
      • Deschler D.G.
      Extracapsular dissection of benign parotid tumors.
      This study has some limitations. No cases of recurrence were identified, probably related to the limited follow-up together with the slow-growing nature of these tumours. A selection bias was also identified, since SP was performed in the more complex cases and for larger tumours, and total parotidectomy cases were not included in the study. Facial nerve weakness, greater auricular nerve weakness, and Frey syndrome were reported on a clinical basis without the use of the House–Brackmann grading system, sensory index score, or starch iodine test, respectively.
      • Martin H.
      • Jayasinghe J.
      • Lowe T.
      Superficial parotidectomy versus extracapsular dissection: literature review and search for a gold standard technique.
      • Hegazy M.A.F.
      • Nahas W.E.
      • Roshdy S.
      Surgical outcome of modified versus conventional parotidectomy in treatment of benign parotid tumors.
      In future studies, the aesthetic outcomes of the surgical incisions could also be investigated. The Milan classification was not used to grade the degree of malignant potential after FNAC. This classification could potentially be used in future studies to objectively grade the FNAC reports in institutions where FNAC is primarily used. As this was a retrospective file analysis, caution is needed when interpreting the reported results.
      In this study, the extracapsular dissection technique showed better clinical outcomes as well as reduced complications when compared to the superficial parotidectomy technique in the selected cases. Therefore, after careful preoperative examination using FNAC, ultrasound, MRI, and clinical evaluation, the extracapsular dissection technique is a suitable alternative to superficial parotidectomy in well indicated and correctly located tumours, namely benign well-defined superficial mobile lesions, especially in the posterior lower lobe. Surgeons should, however, be able to switch between the two surgical modalities when intraoperative findings indicate the need for a more extensive debulking.

      Funding

      None.

      Ethical approval

      The study was approved by the METC Brabant Ethics Committee.

      Competing interests

      None.

      Patient consent

      Patient consent was not required.

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