Should Tumor Depth Measured From an Incisional Biopsy Be Used to Guide the Decision to Perform an Elective Neck Dissection?

Oral squamous cell carcinoma (OSCC) has a propensity for metastasis to neck lymph nodes, an event that halves disease free survival.  The neck metastases are often occult and not detectable by examination or imaging.  Traditionally, an elective neck dissection is used to stage the neck and treat occult metastases in patients whose risk for nodal involvement is greater than 20%[1].  Unfortunately, it is difficult to quantify the risk for nodal metastasis from early stage tumors.  The most commonly used parameter to stratify risk is the depth of invasion[2].  However, the literature that correlates depth of invasion to occult metastases use measurements taken from final pathology.  Practically, most surgeons use measurements taken from incisional biopsies to guide the decision to perform a neck dissection.  Whether the conclusions obtained from data taken from final pathology can be extrapolated to those gathered from incisional biopsy has not been studied.  The first purpose of this study is to identify whether tumor depth from incisional biopsy predicts tumor depth on final pathology.  The second purpose is to determine whether tumor depth from incisional biopsy is predictive of occult metastases.  This is a retrospective chart review of patients with OSCC treated by BLS at UCSF Department of Oral and Maxillofacial Surgery.  All tumors were treated with resection with a 1 cm margin and ipsilateral neck dissection.  Tumor depth or thickness measured on incisional biopsy was compared to those from final tumor resection.  Data was analyzed using a Pearson correlation coefficient.  Tumor depth from incisional biopsy was correlated to occult metastases and neck recurrence.  This was analyzed using both a Wilcoxon two sample test and a Chi-Square test.  A total of 107 patients were included.  The mean age was 64 (30-95). There were 38 T1, 25  T2, 5 T3, and 28 T4 tumors.  25 patients had SCC within the lymph nodes following pathologic evaluation of the neck specimen.  The average tumor depth was 4.69 mm from the incisional biopsy and 10.8 from the final pathology.  No correlation was found between the two with the Pearson coefficient = -0.03, p=0.88).  In addition, poor correlation was shown between tumor depth from incisional biopsy and neck involvement, with the Z score of -0.57, p=0.29 using the Wilcoxon two sample test and the OR = 0.34, p=0.56.  Depth of invasion as measured from an incisional biopsy may not be a reliable tool to predict risk of neck metastases as it does not correlate well with the depth of invasion on final pathology, nor does it predict neck metastases and neck recurrences well.  Given the capricious behavior of OSCC, consideration should be given to recommending elective neck dissection for the majority of patients with OSCC.

1.         Weiss MH, Harrison LB, Isaacs RS: Use of decision analysis in planning a management strategy for the stage N0 neck. Arch Otolaryngol Head Neck Surg 1994;120:699

2.         Po Wing Yuen A, Lam KY, Lam LK et al.: Prognostic factors of clinically stage I and II oral tongue carcinoma-A comparative study of stage, thickness, shape, growth pattern, invasive front malignancy grading, Martinez-Gimeno score, and pathologic features. Head Neck 2002;24:513