Intratumor heterogeneity could inform the use and type of postoperative adjuvant therapy in patients with head and neck squamous cell carcinoma

BACKGROUND After surgery for head and neck squamous cell carcinoma (HNSCC), decisions regarding adjuvant radiotherapy (RT) or chemoradiotherapy (CRT) are based on staging and the presence of high-risk pathology. Because higher mutant allele tumor heterogeneity (MATH; a measure of intratumor genetic heterogeneity) is associated with shorter overall survival (OS) in patients with HNSCC, the authors sought to determine whether MATH analysis might further inform these decisions. METHODS Adjuvant therapy-associated relationships between MATH and OS were analyzed for 389 patients with HNSCC who were treated surgically. Data were obtained from The Cancer Genome Atlas and analyzed with Cox proportional hazards multiple regression accounting for 7 other patient characteristics. RESULTS The relationship between MATH and OS differed with adjuvant therapy in a way that could inform therapy decisions. Adjuvant RT alone was found to provide substantial benefit for patients having high-MATH tumors (RT vs no adjuvant therapy: hazard ratio, 0.29 [95% CI, 0.17-0.51]) but no benefit for those having low-MATH tumors. In contrast, adjuvant CRT provided no benefit beyond that of adjuvant RT for patients with high-MATH tumors but substantially improved OS among patients with low-MATH tumors (CRT vs no adjuvant therapy: hazard ratio, 0.34 [95% CI, 0.15-0.78]). CONCLUSIONS The results of the current analysis suggested that patients with HNSCC with high-MATH tumors who underwent surgical treatment could benefit from adjuvant RT, even when current clinical guidelines indicate otherwise. The addition of adjuvant chemotherapy for patients with high-MATH tumors would not be indicated. Adding chemotherapy might be necessary to radiosensitize low-MATH tumors to adjuvant RT. This potential predictive role of tumor MATH analysis should be evaluated in prospective clinical trials.