A Multi-Institutional Comparison of Carboplatin-Based Regimens Versus Cetuximab in Chemoradiation for p16(-) Head and Neck Cancer

Abstract

When patients cannot receive cisplatin (CP) with definitive radiation therapy (RT) for locally advanced (LA) head and neck squamous cell carcinoma (HNSCC), concurrent cetuximab (C225) is an increasingly popular substitute. However, some studies have shown only marginal tumor control benefit with C225 in p16(-) HNSCC. Carboplatin-based (CB) chemoradiation (CRT) is another alternative to CP-CRT in this population. We hypothesized that CB-CRT would improve locoregional control (LRC) and recurrence-free survival (RFS) compared to C225-RT in cisplatin ineligible p16(-) LA-HNSCC. From two institutions we identified 325 patients with treatment-naïve p16(-) LA-HNSCC (stages III-IVB) of the oropharynx (25.5%), larynx (57.5%), and hypopharynx (16.9%) who received definitive (median 70 Gy) C225-RT (n=65), CB-CRT (n=79; singlet=27, doublet=52), or CP-CRT (n=181) from 2002-2015. Outcomes were estimated with Kaplan-Meier analysis and Cox regression was used to determine the impact of gender, age, smoking, T-stage, N-stage, performance status, comorbidity index, and primary tumor site. Covariates with p<.10 were included in multivariate analysis (MVA) to adjust for confounders. Median age was 61 yrs; ≥T3 (63.7%), ≥N2b (50.2%); median follow up was 51 months. Patient characteristics were balanced between CB-CRT and C225-RT patients; CP-CRT patients were younger (p<.001) and had less comorbidities (p<.001). Respectively, 3-yr outcomes for CP-CRT, CB-CRT, and C225-RT were: LRC (78.0, 81.2, and 49.4%), distant metastasis-free survival (DMFS; 81.4, 84.4, and 71.7%), RFS (67.9, 72.0, and 44.5%), and overall survival (OS; 71.1, 61.0, and 55.1%). On MVA, CB-CRT was associated with improved LRC, RFS, and DMFS, with a trend toward a reduced risk of mortality when compared to C225-RT [table]. Conversely, similar rates of LRC, DMFS, RFS, and OS were noted with CB-CRT and CP-CRT on MVA [table].Abstract 1087; TableLRCDMFSRFSOSAdjusted HR (95%CI)pAdjusted HR (95%CI)pAdjusted HR (95%CI)PAdjusted HR (95%CI)pCB vs CP0.72 (0.37, 1.39)0.330.66 (0.33, 1.30)0.230.73 (0.43, 1.23).241.05 (0.69, 1.59).84C225-RT vs CP2.44 (1.46, 4.08)<.0011.44 (0.78, 2.66)0.251.86 (1.19, 2.89).0061.51 (0.99, 2.32).06C225-RT vs CB3.39 (1.69, 6.76)<.0012.19 (0.99, 4.81)0.052.55 (1.44, 4.52).0011.45 (0.90, 2.34).13 Open table in a new tab When patients cannot receive cisplatin, carboplatin-based CRT is an effective alternative in p16(-) LA-HNSCC. Furthermore, CB-CRT was associated with improved LRC, DMFS, and RFS compared to C225-RT and seems to be a preferred alternative in this population. Prospective validation of these results is needed.