1064P - High-dose versus low-dose cisplatin with definitive concurrent radiotherapy for squamous cell carcinoma of the head and neck (SCC): An analysis of veteran’s health registry data

Abstract

Background: Radiotherapy (RT) with concurrent high-dose cisplatin (HDC) improves outcomes for patients (pts) with SCC. Weekly low-dose cisplatin (LDC) is a widely used alternative approach. The comparative effectiveness and safety of these approaches is unknown. We compared the outcomes of pts treated with HDC and LDC within the Veteran’s Administration Corporate Data Warehouse (CDW). Methods: We identified stage III-IVb SCC patients treated non-surgically with RT and HDC or LDC from 2002 to 2014 in the CDW. Pts were grouped by the dose of their first cycle (HDC vs LDC; intent-to-treat). Variables including cancer site, stage, smoking/alcohol use, and comorbidities were used to generate propensity scores (PS) for the use of HDC. We compared overall survival (OS) by treatment group using Cox regression models, adjusting for PS. We also determined the risk of toxicities using PS-adjusted logistic regression models. Results: A total of 2,820 pts were included in the analysis: 69.7% received HDC (mean initial dose 96 mg/m2). The mean initial dose of LDC was 30 mg/m2. HDC pts were younger (p < 0.001), with lower creatinine (p = 0.002), and lower incidence of baseline neuropathy (p = 0.02). In an unadjusted analysis, HDC was associated with improved OS (Table). After PS adjustment, this difference was no longer statistically significant (p = 0.06). On primary site sub-analysis, HDC provided a benefit only for oropharyngeal primaries (OP). Adjusting for PS, HDC was associated with more renal failure (OR 2.2, 95% CI 1.6-3), neutropenia (OR 2, 95% CI 1.1-3.5), dehydration/electrolyte disturbance (OR 1.3, 95% CI 1.04-1.6), and hearing loss (OR 1.6, 95% CI 1.3-2).Table1064P OS of HDC vs LDCGroupUnadjusted HR for OS95% CIPS Adjusted HR for OS95% CIAll patients (n = 2,820)0.850.77-0.940.890.80-1.01Oral Cavity (n = 182)0.770.56-1.10.720.50-1.10Hypopharynx/Larynx (n = 1,026)1.000.86-1.201.10.90-1.30Oropharynx (n = 1590)0.780.70-0.900.810.69-0.96 Open table in a new tab Conclusions: While HDC does not improve OS over LDC for the overall cohort of patients with SCC receiving RT with definitive intent, it is associated with a survival benefit for patients with OP. HDC is associated with more adverse events. Legal entity responsible for the study: Keith Sigel Funding: None Disclosure: J. Bauml: Research Support: Merck, Bayer, Novartis, Carevive Systems Consulting: Bristol-Myers Squibb, Boehringer Ingelheim, AstraZeneca, Celgene, Genentech, Merck, Guardant Health. C. Aggarwal: Roche, Bristol-Myers Squibb, Eli Lilly: Ad boards Takeda, Macrogenics, Roche: Research support to institution. C.J. Langer: Research: Pfizer, Lilly, Genentech, OSI; GSK; Clovis; Merck; Nektar; Advantagene; Inovio; Takeda; AbbVie Advisor: Bristol-Myers Squibb, ImClone, Pfizer, Lilly; AstraZeneca; Merck; Novartis; Genentech; Bayer; Celgene; Abbott; Biodesix; Clariant; Caris; ARIAD; Boehringer Ingelheim; Synta; Clovis; Amgen; Synta; Peregrine; Incyte. R.B. Cohen: Takeda scientific ad board Zymeworks, Bristol-Myers Squibb. All other authors have declared no conflicts of interest.