|Year : 2018 | Volume
| Issue : 4 | Page : 241-244
Accuracy of preoperative ultrasonography in measuring tumor thickness and predicting the incidence of cervical lymph node metastasis in oral cancer
N Hareesh Babu1, B Vijaya Lakshmi Devi1, Silpa Kadiyala1, AY Lakshmi1, H Narendra2, N Rukmangadha3
1 Department of Radiodiagnosis, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
2 Department of Surgical Oncology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
3 Department of Pathology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
|Date of Web Publication||10-Jan-2019|
Dr. B Vijaya Lakshmi Devi
Department of Radiodiagnosis, SVIMS, Tirupati - 517 507, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Context: A major determinant of the prognosis of oral cancer is the risk of cervical lymph node metastasis. Several factors have been assessed preoperatively to predict the risk of lymph node metastasis; among them, tumor thickness is proved to be a significant predictor of lymph node metastasis. Ultrasonography (US) is a noninvasive, rapid, easily repeatable, and economical examination to measure tumor thickness. This study is undertaken for evaluating the usefulness of US to predict neck metastasis.
Aim: To measure tumor thickness in oral cancer with preoperative US and to predict occult cervical lymph node metastasis.
Materials and Methods: In all, 43 patients with biopsy-proven squamous cell carcinoma of tongue/buccal mucosa underwent preoperative US to measure tumor thickness.
Statistical Analysis: Tumor thickness from histolopathology and US was analyzed using Pearson's product moment correlation. Fisher's exact test was used to assess the relationship between tumor thickness and the risk of cervical lymph node metastasis.
Results: There was a significant correlation between preoperative US and histological measures of tumor thickness (correlation coefficient 0.961, P < 0.001). The overall rate of lymph node metastasis was 25.5% (11/43). In the group with tumors <5 mm in thickness, the neck metastatic rate was 0% (0/5), when compared with 29% (11/38) in the group ≥5 mm. There is difference between the two groups, but it was not statistically significant, P > 0.05.
Conclusion: Preoperative US is an accurate measure of maximal tumor thickness. Tumor thickness ≥5 mm can be considered as a risk factor for cervical lymph nodal metastasis.
Keywords: Cervical lymph node metastasis, oral cancers, tumor thickness, ultrasonography
|How to cite this article:|
Babu N H, Devi B V, Kadiyala S, Lakshmi A Y, Narendra H, Rukmangadha N. Accuracy of preoperative ultrasonography in measuring tumor thickness and predicting the incidence of cervical lymph node metastasis in oral cancer. J NTR Univ Health Sci 2018;7:241-4
|How to cite this URL:|
Babu N H, Devi B V, Kadiyala S, Lakshmi A Y, Narendra H, Rukmangadha N. Accuracy of preoperative ultrasonography in measuring tumor thickness and predicting the incidence of cervical lymph node metastasis in oral cancer. J NTR Univ Health Sci [serial online] 2018 [cited 2019 Jun 17];7:241-4. Available from: http://www.jdrntruhs.org/text.asp?2018/7/4/241/249825
| Introduction|| |
Oral cancer is estimated to be the sixth most common cancer which accounts for 0.6%–5% of all cancers in Europe, the United States, and Australia, and up to 45% of cancers in India. It mainly affects males, with incidence of 75% of patients over age 60 years; but its incidence is growing among females. The oral tongue and floor of the mouth represent about 90% of all oral cavity malignancies. Lymph node metastasis occurs in about 40% of patients with oral cancer and their clinical manifestations are hidden at a rate of 15%–34%.
A major determinant of the prognosis of oral cancer is the risk of cervical lymph node metastasis. The presence of metastatic lymph nodes decreases the survival rate by more than 50%. Several factors have been evaluated for their ability to predict cervical lymph node metastasis. These include tumor stage, shape, thickness, grade, as well as the extent of vascular, lymphatic, and perineural invasion.
To detect tumor thickness preoperatively, various radiological modalities like computed tomography, magnetic resonance, and ultrasonography (US) can be used. US is a noninvasive, rapid, easily repeatable, and economical examination. This study is undertaken for evaluating the usefulness of US as a tool to measure tumor thickness and to predict neck metastasis, to compare tumor thickness measured by US with that of histological specimen, and to correlate tumor thickness by US with incidence of neck metastasis.
| Materials and Methods|| |
This prospective study was conducted in the Department of Radiodiagnosis, SVIMS, Tirupati, during the period of March 2016 to August 2017 and included 43 patients referred from the Department of Surgical Oncology. All of them were biopsy-proven oral squamous cell carcinomas. This study was conducted after obtaining institutional research and ethics committee approval; written informed consent was obtained from all patients.
All patients were surgically staged according to American Joint Committee on Cancer (AJCC) TNM staging system 7th ed.ition, 2010. Intraoral ultrasound examination of the tumor to assess tumor thickness was done on Voluson 730 Pro with sp 6–12 MHz linear array probe. Gel was applied to the transducer tip and the probe was covered with a latex sheath. The probe was then placed directly on the lesion and tumor thickness was measured in a vertical plane from the surface to the nearest millimeter.
US evaluation of all patients was done by a resident doctor under the supervision of one of the two consultant radiologists. Reference measurement of tumor thickness in millimeters was measured in a vertical plane from the surface to the point of maximal depth. In case of exophytic tumor growth, the measurement was taken from the height of the surface with adjacent normal mucosa to the deepest reaching front of infiltration. At the same appointment, US screening of cervical group of lymph nodes was performed to detect levels of lymph node involved and metastasis if present. Patients with clinically negative neck nodes underwent selective neck dissection and those with positive neck nodes underwent modified neck dissection along with primary tumor resection.
Following surgical resection of tumor, the dimension of the gross specimen was recorded and the specimen was sent for histopathological evaluation for estimating tumor thickness and lymph node involvement.
Data were recorded on predesigned proforma and managed using Microsoft Excel Version 14 (Microsoft Corporation, USA) and SPSS Version 17 (Statistical Package for the Social Science; IBM Corporation, USA).
Measurements of tumor thickness from histological specimens and those by US were analyzed using Pearson's product moment correlation to determine the correlation coefficient between them. P value <0.001 was considered as significant.
Fisher's exact test was used to assess the relationship between tumor thickness and the risk of cervical lymph node metastasis. P value <0.05 was considered as significant.
| Results|| |
A total of 43 patients were enrolled in this study, of which 17 were males and 26 were females, and their age ranged from 28 to 72 years with an average of 53.5 years. The TNM staging for all patients is shown in [Table 1].
The measurements of tumor thickness from histological sections and using US were compared; there was a significant correlation between them as displayed in the scatter plot shown in [Figure 1].
Pearson's product moment correlation coefficient was 0.961 (P < 0.001). Tumor thickness on US ranged from 2.5 to 19mm. The average tumor thickness in patients with carcinoma of the right buccal mucosa was 8.6 mm. The average tumor thickness in patients with carcinoma of the left buccal mucosa was 10 mm. The average tumor thickness in patients with carcinoma of the tongue was 8.8 mm.
The correlation of T stage with the risk of cervical metastasis was examined [Table 2]. In the lymph node–negative group, 26 of 32 patients (81%) had T1 or T2 disease. This compared to 4 of 11 (36%) in the lymph node–positive group. In the lymph node–negative group, 6 of the 32 patients (19%) had T3 or T4 disease. This compared to 7 of 11 (64%) in the lymph node–positive group. Cervical metastasis was more common in clinically advanced tumors. The result was statistically significant (P < 0.05) when T1/T2 tumors were compared with T3/T4 tumors. All patients received elective neck dissections. Overall, the rate of lymph node metastasis was 25.5% (11/43) only.
The smallest ultrasound-measured thickness at which cervical nodal metastasis was found was 5 mm. As a result, tumors in this series were divided into two groups, those <5 mm and those ≥5 mm [Table 3]. In the <5 mm group, there were no patients with positive lymph node metastasis, 0% (0/5). In contrast, 29% (11/38) of patients in the ≥5 mm group had positive lymph nodes (28). About 71% (27/38) of patients with tumors ≥5 mm in thickness on US did not develop neck disease. The difference was statistically not significant (P > 0.05).
|Table 3: Ultrasound Tumor Thickness VS Lymphnode Metastasis in Oral Cancer Patients|
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Finally, US lymph node versus histopathological lymph node status was examined. Totally 43 patients were evaluated ultrasonologically for neck nodes. Only 13 of 43 (30%) patients showed positive lymph nodes sonologically, in which 11 of 13 (84.6%) patients showed positive nodes histologically. On ultrasound examination, 33 enlarged lymph nodes in 13 patients were found; 18 of 33 lymph nodes (54.5%) were enlarged in size showing normal morphology; 14 of 33 (42.2%) were enlarged in size and showed abnormal morphology. One of 33 (3%) is subcentimeter in size with abnormal morphology. Among 15 abnormal lymph nodes on US, 10 of 15 (66%) lymph nodes were histologically proved to be metastatic. Among 18 enlarged lymph nodes with normal morphology on US, 3 of 18 (16.6%) were histologically proved as metastatic. The sensitivity of US was 76.9%, specificity of US was 75%, positive predictive value of US was 66%, and negative predictive value of US was 83% for detecting metastatic lymph nodes.
| Discussion|| |
In this series, we confirmed that US is indeed an accurate measure of tumor thickness when compared with histological measurements. This study shows that there is a high positive and significant correlation between ultrasound tumor thickness and histopathological tumor thickness (r = 0.961, P < 0.001); the studies by Mark Taylor et al. and Chammas et al. also showed similar results.
The correlation of T stage with the risk of cervical lymph node metastasis was examined. Univariate analysis showed that the difference between T1/T2 tumors and T3/T4 tumors was significant as expected; the risk increases with more advanced tumors. The studies by Mark Taylor et al. and Woolgar and Scott showed similar findings.
The relationship between tumor thickness and the risk of cervical lymph node metastasis was examined. In our study, the smallest ultrasound-measured thickness at which cervical nodal metastasis was found was 5 mm. As a result, tumors in this series were divided into two groups, those <5 mm and those ≥5 mm. In the <5 mm group, there were no patients with positive lymph node metastasis (0/5). In contrast, 29% (11/38) of patients in the ≥5 mm group had positive lymph nodes. About 71% (6/17) of patients with tumors ≥5 mm in thickness on US did not develop neck disease. A univariate analysis between the two groups showed no statistically significant difference. Our study does not support the previously reported (by Mark Taylor et al., Kane et al.) correlation between tumor thickness and nodal metastasis.
In this study, US yielded a sensitivity, specificity, positive, and negative predictive value of 76.9%, 75%, 83%, and 76.9%, respectively, for detecting lymph nodal metastasis. Our study findings are comparable with the studies by Sureshkannan et al. and Shetty et al.
The sample size was less in our study and further validation is required with higher samples. Also, this was a single-institutional study.
| Conclusion|| |
Preoperative US is an accurate measure of maximal tumor thickness. Tumor thickness ≥5 mm can be considered as a risk factor for cervical lymph nodal metastasis.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]