Triweekly carboplatin as a potential de-intensification agent in concurrent chemoradiation for early-stage HPV-associated oropharyngeal cancer.

Objective: We compared high-dose cisplatin (HDC) vs. triweekly carboplatin (TC)-based chemoradiation in patients with HPV-associated oropharyngeal squamous cell carcinoma (OPSCC).

Materials And Methods: A retrospective review was conducted from 2006 to 2015 of 421 patients with locally advanced p16-positive OPSCC receiving definitive radiotherapy concurrent with 3 cycles of HDC (100 mg/m, n = 230) or TC (AUC = 5, n = 191). Three-year locoregional recurrence (LRR), distant metastasis (DM), overall recurrence rate (ORR), overall survival (OS), and cause-specific survival (CSS) are reported. HDC and TC were compared accounting for age, sex, comorbidity index score, smoking history, T stage, and N stage.

Results: For all-comers, no difference was observed between HDC and TC for any outcome except for ORR which was lower in patients receiving HDC (12% vs. 17%, p = 0.03). On stage-based analysis, no difference was observed between agents for any outcome for stage I or II disease. However, patients with stage III disease receiving HDC had lower rates of LRR (9% vs. 21%, p = 0.03), DM (7% vs. 28%, p = 0.006), and ORR (14% vs. 40%, p = 0.002), and superior OS (89% vs. 78%, p = 0.04) and CSS (95% vs. 80%, p = 0.02). Patients receiving HDC experienced higher rates of grade 3 leukopenia (25% vs. 11%, p < 0.001), weight loss ≥20% from baseline (21% vs. 8%, p < 0.001), and gastrostomy-tube placements (66% vs. 27%, p < 0.001).

Conclusion: TC demonstrated comparable outcomes to HDC for stage I or II HPV-associated OPSCC but was inferior to HDC for stage III disease. TC was associated with less toxicity and may be a potential de-intensification agent for early-stage disease.