1127P - Brachytherapy and non-cancer mortality in patients with oral cavity and oropharynx SCCs

Abstract

BackgroundOral cavity and oropharyngeal squamous cell cancers (OC-OPSCC) display high cancer mortality. Aspiration, infection, other complications or treatment, and age- and substance-related comorbidities contribute to non-cancer mortality. This single-institution study examines cause of death in patients treated for OC-OPSCC with brachytherapy, chemotherapy, external beam radiation, surgery, or combination of modalities. We hypothesize that brachytherapy results in lower non-cancer mortality. MethodsIRB approval was obtained. Our institution’s Tumor Registry and electronic medical record were used to identify patients with a first OC-OPSCC diagnosis between 2000-2010. Patients with a second primary cancer at diagnosis were excluded. The primary outcome was association between treatment modality and non-cancer mortality. Secondary outcomes were effects of comorbidities on death, specific causes of non-cancer mortality, and cancer mortality. ResultsOf 693 eligible patients, 460 were deceased. 84 died of the primary malignancy. Non-primary cancer cause of death was determined in 96 patients; 24 died from a second primary. 193 patients received brachytherapy. Cox proportional hazards regression was performed on treatment regimen, exposures, and non-cancer mortality, stratified by AJCC stage, race, and sex. Age, smoking, and alcohol were associated with worse survival, with HRs of 1.03 (p<0.005), 1.36 (p<0.11), and 2.23 (p<0.005), respectively. Brachytherapy had a notable 0.52HR (p<0.005). Non-smoking OPC patients had a 76% 5-year overall survival (OS), suggesting these were largely HPV-driven cancers. In smokers with OPC, OS was 33% at 5 years, with a HR of 0.35 for brachytherapy-treated patients. ConclusionsWe report non-cancer mortality from an extensively annotated cohort of curatively treated OC-OPSCC. We show a significant correlation between receipt of brachytherapy and non-cancer survival, independent of remission status. Potential explanations include improved disease control, patient selection, and reduced exposure to external beam radiation. Although HPV status was not available, OPC in non-smokers displayed OS characteristic for HPV-associated cancer. The impact of brachytherapy in OPC was strongest in smokers. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureS. Mehra: Research grant / Funding (institution): DePuy Synthes Educational Grant for Yale Head and Neck Surgery Fellowship. B. Burtness: Advisory / Consultancy: Aduro; Advisory / Consultancy: Alligator Biosciences; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Boehringer Ingelheim; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Celgene; Advisory / Consultancy: Cue Biopharma; Advisory / Consultancy: Genentech/Roche; Advisory / Consultancy: Glaxo Smith Kline; Advisory / Consultancy: IDDI; Advisory / Consultancy: Merck. All other authors have declared no conflicts of interest.