International Journal of Oral & Maxillofacial Surgery
Volume 39, Issue 5 , Pages 486-492, May 2010

Colorimetric analysis of unstained lesions surrounding oral squamous cell carcinomas and oral potentially malignant disorders using iodine

  • K. Maeda

      Affiliations

    • Maxillofacial Surgery, Maxillofacial Reconstruction and Function, Division of Maxillofacial and Neck Reconstruction
    • Corresponding Author InformationAddress: Keiko Maeda, Maxillofacial Surgery, Maxillofacial Reconstruction and Function, Division of Maxillofacial and Neck Reconstruction, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan 113-8549, Tel.: +81 (3) 5803 5500; Fax: +81 (3) 5803 0298.
    • ,
  • T. Suzuki

      Affiliations

    • Maxillofacial Surgery, Maxillofacial Reconstruction and Function, Division of Maxillofacial and Neck Reconstruction
    • ,
  • Y. Ooyama

      Affiliations

    • Maxillofacial Surgery, Maxillofacial Reconstruction and Function, Division of Maxillofacial and Neck Reconstruction
    • ,
  • K. Nakakuki

      Affiliations

    • Maxillofacial Surgery, Maxillofacial Reconstruction and Function, Division of Maxillofacial and Neck Reconstruction
    • ,
  • M. Yamashiro

      Affiliations

    • Maxillofacial Surgery, Maxillofacial Reconstruction and Function, Division of Maxillofacial and Neck Reconstruction
    • ,
  • N. Okada

      Affiliations

    • Diagnostic Oral Pathology, Oral Restitution, Oral Health Science, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan
    • ,
  • T. Amagasa

      Affiliations

    • Maxillofacial Surgery, Maxillofacial Reconstruction and Function, Division of Maxillofacial and Neck Reconstruction

Accepted 2 November 2009. published online 07 December 2009.

Article Outline

Abstract 

To determine whether the measurement of staining with 3% Lugol's solution provided efficient criteria for determining the area of resection for oral carcinomas and oral potentially malignant disorders, the authors analyzed the color of unstained lesions (USLs) in relation to histopathological findings. After vital iodine staining, USLs were seen in 48 of 54 patients (88.9%). A significant difference was seen in the value of lightness between stained lesions (SLs) and USLs for patients with moderate and severe epithelial dysplasia (P<0.001). The deviation between the macroscopically observable and the histopathological boundaries was −0.65±1.26mm (range: −4.36 to 1.52). Color charts prepared on the basis of values for lightness and hue reproduced the macroscopic color differences in USLs, suggesting that it may become possible to diagnose USLs histologically on the basis of the measured color values and use of color charts to help determine the resection area in surgery.

Keywords: oral squamous cell carcinoma, oral potentially malignant disorders, vital iodine staining, iodine unstained lesions, color measurement, color chart

 

Oral cancer, especially oral squamous cell carcinoma (OSCC) is the most common head and neck cancer and is found in 270,000 patients annually worldwide19. The American Cancer Society has set a goal of reducing the morbidity of oral cancer by 25% in the US between 1992 and 2015 and has shown a drop from 12.0% to 10.7% (mean change per year: −0.9%) in its interim report24, but the 5-year survival rate has not improved in more than two decades9. In the case of malignant tumors, early detection and early treatment are important to improve the survival rates of patients with oral cancer.

Vital iodine staining can be used immediately before resection as a useful and minimally invasive test for determining the area of resection for esophageal cancer7, 10, 17, 26. In this staining technique, iodine binds to glycogen granules in the cytoplasm of squamous cells, and this reaction results in a black–brown color. Many studies have shown that glycolysis is elevated in cancer cells1, 5, 11, and such cellular areas with elevated glycolysis are generally seen as unstained lesions (USLs) during vital iodine staining. Since vital iodine staining was first performed on the cervix23 and esophageal mucosa30, it has been combined routinely with endoscopy of the upper gastrointestinal tract, and it has contributed markedly to the early detection of esophageal cancer7, 26.

The oral mucosa, the lining of which is made up of non-keratinizing stratified squamous epithelium (buccal mucosa, oral vestibule, ventral surface of the tongue [lateral margin to the inferior surface], floor of the mouth and soft palate) is stained with iodine; but the masticatory mucosa (attached gingiva and hard palate) and specialized mucosa (dorsal lingual mucosa) are not18. Compared with the upper gastrointestinal tract, the thickness of the mucosal epithelium varies in the oral cavity (100–500μm), and the presence of teeth, saliva and movement of the tongue make it difficult to observe tissue samples under similar conditions.

The objectives of the present study were to analyze the color of USLs in the vicinity of oral carcinomas and oral potentially malignant disorders (OPMD) in relation to histopathological findings, and to determine whether the color measurement provided efficient criteria for determining the resection area for treatment of these cancers.

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Patients and methods 

Fifty-four patients who had conditions diagnosed as OSCC or OPMD and who underwent biopsy or surgery under general anesthesia at the Tokyo Medical and Dental University Hospital Faculty of Dentistry from July 2007 to September 2008 were included in this study. The inclusion criteria were: OSCC patients classified in the T1 or T2 category; OPMD patients who underwent biopsy for definite diagnosis or were selected for surgical treatment; patients whose lesions were measureable and could be illuminated by an artificial sunlight lamp. The mean age of the patients was 60.7 years (range 25–83 years), and their clinicopathological features are shown in Table 1. This study was approved by the Ethics Review Board of the Faculty of Dentistry (NO.277). The study was explained to all patients and informed consent was obtained from them. Clinical staging was performed on the basis of the International Union Against Cancer (UICC)28, and oral leukoplakia was classified according to WHO criteria22.

Table 1. Clinicopathological features of patients (n=54).
CharacteristicNo.
Age (years)
<6023
≧6031

Sex
Male32
Female22

Site of disease
Tongue46
Buccal mucosa4
Soft Palate3
Oral Vestibule1

Histological diagnosis
OSCCa38
OLb15
Epithelial hyperplasia1

TNM classification of OSCC
T category
T120
T218
N category
N035
N13

Classification of OL
homogeneous11
nonhomogeneous4

aOSCC, oral squamous cell carcinoma.

bOL, oral leukoplakia.

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Staining solutions and procedures 

A 3% Lugol's solution containing 3g of iodine, 6g of potassium iodine, and 100ml of distilled water was used for staining according to the following procedure. First, the untreated lesion was photographed, and the colorimeter (CS-100, Konica Minolta Holdings, Inc., Tokyo, Japan) was calibrated in the oral cavity. The 3% Lugol's solution was applied, and the area was rinsed with water and dried. Color measurement was performed after 2min, and the USLs were photographed. Sodium thiosulfate was applied. USLs were defined as uncolored areas that appeared after iodine staining, excluding macroscopically observable white lesions and tumorous areas. Stained lesions (SLs) were defined as colored normal mucosa that appeared proximate to USLs.

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Tissue processing and evaluation 

A shallow incision was made using a scalpel in 34 patients who had a clear, straight border between the unstained and stained mucosa (Fig. 1A). After fixing in 10% buffered formalin, 4-μm sections were stained using hematoxylin-eosin (H-E) in all cases. For histopathological evaluation of USLs, epithelial dysplasia was classified as mild, moderate or severe according to WHO standards.22 If atypical findings were not observed, hyperkeratosis and acanthosis of the simple elongated epithelial layer were grouped into epithelial hyperplasia. Periodic acid Schiff (PAS) staining and PAS staining following enzymatic digestion with 0.1% α-amylase were performed. A histopathological diagnosis was made (Fig. 1B) on the basis of these stained sections. To evaluate the boundaries between USLs and SLs, the number of PAS-positive cells in the non-keratinizing epithelial layer was counted over a 25mm2 area for USLs/SLs and surgical margin areas, which were defined as tissue within 5mm from the boundary line and the adjacent surgical margin, respectively, using an eyepiece micrometer (U-OCMSQ10/10, Olympus, Inc., Tokyo, Japan) at a magnification of×200. The percentage of PAS-positive cells was calculated. The authors defined the deviation as the distance between the macroscopically observable boundary and the histological boundary, measured as the distance from the superficial incision to the normal epithelial layer (Fig. 1C,D). The status of all resection margins was examined in permanent paraffin sections.

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  • Fig. 1. 

    Processing and evaluation of tissue. (A) Specimen after resection (Patient No. 44: oral squamous cell carcinoma; T2N0M0). Circle and black line indicate color measuring point for USLs and cut mark of boundary line between SLs and USLs, respectively. (B) Histopathological diagnosis corresponding to sections of specimen. Arrows indicate surgical margin area defined as the tissue surrounding the adjacent marginal area. Yellow line, mild epithelial dysplasia; green line, moderate epithelial dysplasia; pink line, severe epithelial dysplasia; red cross, cancerous lesions; black line, cut mark of boundary line between SLs and USLs; white circle, color measuring point for USLs. (C) Arrow indicates shallow incision in the specimen showing macroscopic boundary line between SLs and USLs (H-E staining ×40). (D) Schema for measurement of deviation. The deviation was defined as the distance between the macroscopic and histopathological boundary lines. The histopathological border in the specimen is indicated by the zero point.

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Color measurement 

Color was measured using a colorimeter (CS-100, Konica Minolta Holdings, Inc., Japan) according to the method of Yamashiro32 as follows: an artificial sunlight lamp (SOLAX XC-100, Seric Ltd., Tokyo, Japan) was used to illuminate the lesion at a 45° angle and a distance of 1 m, and color was measured in the vertical direction. A close-up lens No.122 (measurement diameter 3.2–4.3mm) was attached to the colorimeter and color was measured within the wavelength range of 323–368mm. Numerical values were recorded using the data processor DP-101 (Konica Minolta Holdings, Inc., Japan). Measuring points of USLs and SLs were defined as the area within 10mm from the boundary line. In each test, five measurements were taken to eliminate marked variations and an average value was calculated. D55 was used as the light source and data were calculated in the Y, x, y mode. Using a dental mirror-type standard white board, an arbitrary standard calibration was carried out under the same conditions as the test areas. For sanitation, fingertips cut from disposable, sterilized gloves were used to cover the areas and were changed for each patient.

The CIE L*a*b* color system recommended by the Commission Internationale dl’Eclairage in 1976 is used to describe the developed color. With this system, L* indicates lightness and a* and b* indicate hue. The following formulas are used for converting Y, x, y into L*, a*, b*12.

Color differences refer to the quantitative differences in color perception and were calculated using the following formula:

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Data and statistical analysis 

Color difference () was assessed on the basis of National Bureau of Standards (NBS) units, as reported by Koksal16 and Seghi25. The criteria for categorization were: trace (0–0.5), slight (0.5–1.5), noticeable (1.5–3.0), appreciable (3.0–6.0), strong (6.0–12.0) and very strong (>12.0). Adobe Photoshop 7.0 (Adobe Systems Inc., San Jose, CA, USA) was used for the composition of color charts. Data were analyzed using SPSS 16.0J statistical software (SPSS Inc., Chicago, IL, USA), and values were expressed as mean±standard deviation (SD). Tukey's and Dunnett's multiple comparison tests were conducted, and the level of significance was set at P<0.05 (two sided).

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Results 

Histopathological classification of USLs and margin status 

USLs were seen in 48 of 54 patients (88.9%). The histopathological diagnoses for the 48 patients with detected USLs were epithelial hyperplasia in 7 patients (14.6%), mild epithelial dysplasia in 13 patients (27.1%) (Fig. 2A–D), moderate epithelial dysplasia in 20 patients (41.7%) (Fig. 2 E–H) and severe epithelial dysplasia in 8 patients (16.7%) (Fig. 2 I–L). Table 2 shows a summary of the results of classification of USLs. Diagnoses of the resection margins were made on the basis of the examination of the paraffin embedded slides, and all of them were negative for severe dysplasia except one case. The USLs of this patient extended to the oropharynx and the histopathological analysis showed that the USLs were moderate epithelial dysplasia. Local recurrence was observed after about 6 months, and another 53 patients remained disease-free after a median follow-up of 15 months (range 9–23 months).

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  • Fig. 2. 

    Staining results and histopathological examinations. Case 1 (A–D): (A) Condition clinically diagnosed as OSCC of the tongue (T2N0M0). (B) Iodine staining result. Measuring point for the color of the USLs is indicated by the asterisk. (C) SLs (PAS staining ×100). (D) Mild epithelial dysplasia (PAS staining ×100). The epithelial layer has hardly any stained cells and there are a few atypical cells in the basal layer. Case 2 (E–H): (E) Condition was diagnosed as OSCC of the tongue (T3N0M0). (F) Iodine staining result. Measuring point for the color of the USLs is indicated by the circle. (G) SLs (PAS staining ×100). (H) Moderate epithelial dysplasia (PAS staining ×100). Loss of the polarity of basal cells and irregular epithermal stratification were remarkable compared with those observed in mild epithelial dysplasia. Case 3 (I–L): (I) Condition was diagnosed as OSCC of the tongue (T2N0M0). (J) Iodine staining result. Measuring point for the color of the USLs is indicated by the circle. (K) SLs (PAS staining ×200). (L) Severe epithelial dysplasia (PAS staining ×200). Nuclear hyperchromatism and increased nuclear–cytoplasmic ratio in cells were found. Each white square indicates SLs (control) adjacent to USLs.

Table 2. Histopathogical classification of USLs (n=48).
HYPMLDMODSED
Histopathogical diagnosis of primary lesionn(%)n(%)n(%)n(%)
OSCC2(28.6)9(69.2)15(75.0)6(75.0)
OL4(57.1)4(30.8)5(25.0)2(25.0)
HYP1(14.3)

Total7(14.6)13(27.1)20(41.7)8(16.7)

OSCC: oral squamous cell carcinoma, OL; oral leukoplakia, HYP: epithelial hyperplasia, MLD: mild epithelial dysplasia, MOD: moderate epithelial dysplasia, SED: severe epithelial dysplasia.

Measurement of color value and chart of USLs 

USLs were seen in 40 patients with tongue OSCC/OPMD, and Table 3 summarizes the results of each measurement. When compared with the stained normal area, significant differences were seen in the L* (lightness) values in patients with moderate to severe epithelial dysplasia (41.04±6.92: P<0.001). The color difference ( units) between SLs and USLs was 7.56±4.53 in patients with epithelial hyperplasia, 8.55±4.20 in those with mild epithelial dysplasia, and 15.05±5.85 in those with moderate to severe epithelial dysplasia. The color difference () units for epithelial hyperplasia and mild epithelial dysplasia were assessed as ‘strong’, and that for moderate to severe epithelial dysplasia was assessed as ‘very strong’. There were significant differences between moderate to severe epithelial dysplasia and epithelial hyperplasia (P=0.035), and between moderate to severe epithelial dysplasia and mild epithelial dysplasia (P=0.005). There was no significant difference between the epithelial hyperplasia and mild epithelial dysplasia groups (P=0.946). Using the L*, a* and b* values, color charts representing the color differences of observable USLs in the intraoral area were reproduced (Fig. 3).

Table 3. Color values and tongue differences after staining (n=40).
L*a*b*
nmean±SDP-valuemean±SDP-valuemean±SDP-valuemean±SD(range)
SLs (Control) 4032.01±7.20 25.46±4.58 21.31±7.49
USLsHYP539.11±8.780.10725.54±2.471.00025.70±10.100.4787.56±4.53 a(1.68–11.47)
MLD1137.66±5.090.07926.12±3.640.89722.38±8.810.8898.55±4.20 b(2.88–13.95)
MOD/SED2441.04±6.92<0.00126.64±4.930.54424.73±5.450.13715.05±5.85(4.28–26.32)

SLs, stained normal epithelial mucosa; USLs, unstained lesions; HYP, epithelial hyperplasia; MLD, mild epithelial dysplasia; MOD/SED, moderate to severe epithelial dysplasia. SD, standard deviation. P-values of color values (L*, a*, b*) are from Dunnett's multiple comparison test and color differences () are from Tukey's multiple comparison test. Differences considered significant at the P<0.05 level (two-sided).

aThere was significant difference between HYP and MOD/SED (P=0.035) and no significant difference between HYP and MLD groups (P=0.946).

bThere was significant difference between MLD and MOD/SED groups (P=0.005).

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  • Fig. 3. 

    Color charts of results of tongue stained with 3% Lugol's solution. (a) normal stained area, (b) mild epithelial dysplasia, (c) moderate to severe epithelial dysplasia.

PAS staining and deviation 

Enzymatic digestion with 0.1% α-amylase was performed in all cases before PAS staining was carried out (n=34), and saccharide digestion was confirmed in all cases. The ratios of PAS-positive cells for the USLs in patients with epithelial hyperplasia (n=5), mild epithelial dysplasia (n=11), and moderate to severe epithelial dysplasia (n=18) were 39.6±33.3, 18.8±16.6 and 14.3±12.0 (%), and those for the USLs, SLs and surgical margin area were 19.8±19.0, 55.6±22.1 and 75.4±15.4 (%), respectively (Fig. 4). Tukey's multiple comparison tests were conducted, and there were significant differences between USLs and SLs (P<0.001), and between USLs and surgical margin area (P<0.001). In the classification of the histopathological diagnosis of USLs, there was a significant difference between epithelial hyperplasia and moderate to severe epithelial dysplasia (P=0.035). No significant difference was evident between epithelial hyperplasia and mild epithelial dysplasia (P=0.119). The deviation between the macroscopically observable boundary and the histological boundary was −0.65±1.26mm (mean±SD; range: −4.36–1.52).

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  • Fig. 4. 

    Rates (%) of PAS-stained cells (n=34). (A) Shows USLs, SLs and surgical margin area (SMA). (B) Shows epithelial hyperplasia (HYP, n=5), mild epithelial dysplasia (MLD, n=11), moderate to severe epithelial dysplasia (MOD/SED, n=18). The results are presented as means±SD (bars). Tukey's multiple comparison test (* P<0.05) was used for statistical analysis. In (A) there were significant differences between USLs and SLs (**P<0.001), USLs and SMA (**P<0.001). In (B) there was a significant difference between HYP and MOD/SED (*P=0.035). No significant difference was evident between HYP and MLD (P=0.119).

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Discussion 

Studies have been conducted using vital iodine staining and endoscopy in the upper gastrointestinal tract and oral cavities in which malignant lesions have been detected, and USLs have been histopathologically classified7, 10, 13, 17, 26, 27, 29. To the best of the authors’ knowledge, there have been few studies objectively quantifying the color of the USLs observed using these techniques8, 14. Kerawara et al.15 reported a study of vital staining in the oral cavity using 1% toluidine blue and its usefulness in identifying invasive tumors at the resection margins. These authors suggested that there was no benefit to vital staining in identifying dysplasia at such margins. In the present study, the color of USLs identified using 3% Lugol's solution in patients with OSCC or OPMD was measured, analyzed and compared with that of the adjacent stained areas. The authors also attempted to measure the color of the primary lesions, but various superficial properties such as bleeding, the presence of ulcers and different developmental types prevented measurement under totally uniform conditions.

USLs were seen at a high rate (88.9%) because the main lesion was confirmed by preoperative biopsy and iodine staining was performed in patients with a clinical diagnosis of mainly OSCC or OPMD. In the histopathological classification of USLs, moderate to severe epithelial dysplasia was confirmed in the majority of USLs (58.3%) and predominantly in patients with OSCC (Table 2).

The values of L*, a* and b* indicate lightness and a color range from green to red and blue to yellow, respectively. Among them, only the L* value showed a significant difference between stained normal epithelial mucosa (32.01±7.20) and lesions of moderate to severe epithelial dysplasia (41.04±6.92, P<0.001). The color difference () between precancerous/white lesions and normal oral mucosa (red to pink) is difficult to determine macroscopically; however, iodine staining allows easier detection of USLs with a clear border. Seghi et al.25 concluded that the clinically acceptable limit in color differences in the oral cavity ranged from 2.8 to 3.7 units, whereas Du et al. 8 reported that differences of more than 8.0 units were easy to identify under intraoral conditions. The color differences between the adjacent stained normal mucosa and USLs in the patients with epithelial hyperplasia, mild epithelial dysplasia and moderate to severe epithelial dysplasia were 7.56±4.53, 8.55±4.20, and 15.05±5.85 units, respectively; thus, marked contrasts could be confirmed, especially in patients with moderate to severe epithelial dysplasia whose fell more into the category of ‘very strong’. Epithelial hyperplasia occurred in 5 of 40 patients with OSCC or oral leukoplakia of the tongue (12.5%), and the L* value was relatively similar to that of moderate to severe epithelial dysplasia. To discriminate epithelial hyperplasia from moderate to severe epithelial dysplasia, the use of the color difference value () is suggested, because the value of was lower in patients with epithelial hyperplasia (7.56±4.53) than in patients with moderate to severe epithelial dysplasia (15.05±5.85; P=0.035). The USLs in the epithelial hyperplasia lesions and surrounding normal epithelial areas both probably consume a large amount of glycogen for their hyperplasia, resulting in the lower color difference.

USLs detected by iodine staining around OSCC and leukoplakia in the oral cavity were macroscopically analyzed, and their colors were quantified and reproduced outside the oral cavity by preparing color charts. These were prepared on the basis of the results of the values of L*, a* and b* after iodine staining (Fig. 3). It would be possible to distinguish the colors of the USLs and the stained normal areas using these charts.

In patients with moderate to severe epithelial dysplasia, the ratio of cells that stained positively with PAS in USLs was markedly low at 14.3±12.0 (%), and that for surgical margin area was 75.4±15.4 (%). When the histological types of the USLs were compared, there were significant differences between patients with epithelial hyperplasia and moderate to severe epithelial dysplasia (P=0.035). This may indicate that glycolysis in moderate to severe epithelial dysplasia lesions was more prominent. The reason for the low grade of staining in the surgical margin areas could have been formalin fixation and the elimination of glycogen by water rinsing. When determining the area of resection, it should be borne in mind that the amount of glycogen in cells around the cancer is lower than in healthy normal cells.

Yokoo et al.33 reported that because proliferating cell nuclear antigen (PCNA) and p53 in USLs have similar immunostaining patterns in mild epithelial dysplasia and controls, and in moderate and severe epithelial dysplasia, they can be divided into two categories; specifically, the former for almost normal regions and the latter for regions with suspected malignancies. The present results support these findings.

It is desirable to minimize resection to obtain a favorable postoperative quality of life (QOL), because the oral cavity is involved in mastication, speech and swallowing, and is esthetically important. There is no standard for the distance between the surgical margin and the border of the USLs. In patients with OPMD, the predominant disease is leukoplakia in the oral regions, with differing types of treatments31. The rate of annual malignant conversion of oral leukoplakia was reported as 1.36% (95% CI; 0.69–2.03%) by Petti21. USLs with epithelial dysplasia should be resected with adequate margins.

Brandwein-Gensler et al.4 reported that the status of the resection margin alone was not an independent predictor of local recurrence of OSCC. The patterns of invasion and lymphocyte response were more significant factors predicting local recurrence than the margin status. Although margin status is not always a necessary and sufficient factor for predicting a postoperative disease-free condition, the authors considered it to be a prerequisite for good prognosis.

Frozen sections have been used for perioperative rapid assessment of margins and these results cause unavoidable expansion of the resection range, whereas the final margin status usually influences the decision about postoperative adjuvant therapy. The use of frozen sections is in dispute because of discrepancies between the frozen section report and the final margin status and the difficulty of establishing a mutual understanding between surgeons and pathologists of the various pieces of information in a small segment of tissue3, 20. Some reports have shown that adding intraoperative imprint cytology can be more useful than frozen sections alone for diagnostic accuracy2, 6. Compared with the use of frozen sections, the main advantage of the color measuring technique is the ability of the surgeon alone to acquire histopathological information about the USLs and surrounding surgical margins by closely observing the area in the oral cavity. This method also requires less time for diagnosis.

The authors defined the deviation as the distance between the macroscopically observable and histologic boundaries. The boundaries of USLs were generally corrugated or wrinkled; 34 patients had clear flat boundary lines and the distance from the superficial incision to the normal epithelial layer was measured. The measured deviation range was from −4.36 to 1.52mm (mean±SD; −0.65±1.26). The mean of deviation was no more than 1mm from the macroscopically observable boundary and almost coincided with the histological boundary. The maximum observed deviation was −4.36mm and these USLs were diagnosed as mild epithelial dysplasia histopathologically. In this study, all resection margins were reported to be negative for severe dysplasia in the final histopathological reports except for one case. Patient No. 2 with tongue SCC (T1N0M0) had USLs more than 50mm in size, reaching as far as the pharynx; partial resection was performed as widely as possible, but local recurrence was confirmed within about 6 months. The authors usually maintain a surgical margin of 5–8mm away from the boundary line of USLs, and the present data proved that this was practical.

In conclusion, although this was a pilot study, 53 (98.1%) patients remained disease-free after a median follow-up of 15 months (range 9–23 months), which the authors consider is a promising indication of potential clinical applicability. Additional studies with longer follow-up to further document the rate of surgical margins and improved local control should be undertaken to demonstrate whether it will be possible to predict the histopathological findings with better precision for USLs surrounding OSCC and oral leukoplakia preoperatively or perioperatively on the basis of the measured color values. This will allow the minimum necessary resection area to be determined more easily and precisely.

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Competing interests 

None declared.

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Funding 

None.

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Ethical approval 

Not required.

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PII: S0901-5027(09)01147-3

doi:10.1016/j.ijom.2009.11.001

International Journal of Oral & Maxillofacial Surgery
Volume 39, Issue 5 , Pages 486-492, May 2010

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