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-specific mortality and increased non-cancer mortality. We examined cause of death in patients treated for OC-OPSCC with brachytherapy, chemotherapy, external beam radiation, surgery, or combination of modalities. We hypothesized that brachytherapy does not increase non-cancer mortality comparably with external beam radiation.

Methods: A database was constructed from institutional tumor registry and electronic medical record data from all patients with first OC-OPSCC diagnosis at our institution between 2000 and 2010, excluding patients with a second primary cancer at diagnosis. The primary outcome was association between treatment modality and non-cancer mortality.

Results: Of 693 eligible patients, 460 were deceased; 84 from primary malignancy and 96 from a non-primary cancer cause, including 24 with a second primary cancer. 193 patients received brachytherapy. Cox proportional hazards regression was performed on treatment regimen, stratified by AJCC stage, race, and sex. Age, smoking history, and alcohol had HRs for death of 1.05 (p < 0.005), 1.37 (p = 0.106), and 2.24 (p < 0.005), respectively, while brachytherapy had a 0.53 HR (p < 0.005) for death. Non-smoking OPC patients had an 88% 5-year OS, suggesting these were largely HPV-driven cancers. In smoking OPC patients, 5-year OS was 61%. Non-cancer mortality HR of 0.36 for brachytherapy-treated patients.

Conclusion: We report non-cancer mortality from a cohort of curatively treated OC-OPSCC and show a significant correlation between brachytherapy and non-cancer survival, independent of remission status. The impact of brachytherapy in OPC was strongest in smokers.