Impact of Residual Adenopathy Following Chemoradiotherapy for SquamousCell Carcinoma of the Head and Neck: A Retrospective Analysis of 51Consecutive Cases

Locally advanced squamous cell carcinoma of the head and neck is commonly treated with chemoradiotherapy (CRT). It remains uncertain if residual adenopathy (RA), greater than 1 cm in maximal dimension, detected by computerized tomography following treatment has an impact on outcome. Similarly, the utility of neck dissection (ND) to pathologically evaluate RA remains undefined. We performed a retrospective analysis to assess the frequency and impact of RA and the utility of ND in SCCHN. A query of the electronic medical record using ICD9 codes was performed to identify patients that met the following inclusion criteria: age greater than 18 years, a histologically proven SCCHN diagnosed between 2003 and 2013, N1 to N3 disease, and treatment with CRT. Clinical data were abstracted through chart review. Progression free (PFS) and overall survival (OS) were estimated using Kaplan Meier analysis, and comparisons were made with log rank test. Chi-square and receiver operating characteristics were used to assess size of RA as a predictive factor. One hundred twenty three patient charts were reviewed and ninety-nine complete patient records were available for analysis. The median age at diagnosis was 56 years. Eight percent had N1 disease, 86% had N2, and 5% had N3. Following completion of CRT, 51 patients (51%) had RA. Of these, 41 patients underwent a ND, and 8 (19.5%) were found to have residual malignancy. At a median follow up of 35 months, there was no difference in PFS or OS in the patients who had radiological RA (p=0.37 and 0.72) or pathologically proven residual disease compared to those who did not. Residual adenopathy was not a predictor of residual pathologic disease. Size of RA was a poor predictor of residual cancer (AUC=0.637). Of the 48 patients tested for p16, 77% were positive by immunohistochemistry. Patients with p16 positive tumors appeared to have superior OS (p=0.038), but there was no impact on PFS (p=0.27) compared to those that were negative. Following CRT, while many patients have RA, only a small subset (19.5%) has residual active cancer. The presence of either does not impact PFS or OS. Moreover, using RA greater than 1 cm as a threshold to perform an ND lacks specificity in identifying those with pathologically positive residual cancer. These data suggest ND may be safely avoided in most patients and will help inform future prospective trials using alternative imaging modalities, such as PET/CT, to identify the subset of patients most likely to benefit from ND.