3985 - Brachytherapy and non-cancer mortality in patients with oral cavity and oropharynx SCCs

Background

Oral 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.

Methods

IRB 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.

Results

Of 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 0.52 HR (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.

Conclusions

We 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.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

S. 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.