Association of low adherence to weekly cisplatin with outcomes in patients with head and neck squamous cell carcinoma: a retrospective cohort study

Background The National Comprehensive Cancer Network (NCCN) guideline recommends consideration of weekly cisplatin as an alternative option for patients with head and neck cancer undergoing definitive chemoradiation. However, in a recent phase III trial (ConCERT), 20% of patients treated with weekly cisplatin could not receive a total of 200 mg/m2, and the association of low adherence to weekly cisplatin and cancer control outcomes remains unclear. To fill this knowledge gap, we performed an observational cohort study of patients with head and neck cancer undergoing definitive chemoradiation with weekly cisplatin. Methods Our institutional database was queried for patients with non-metastatic head and neck cancer who underwent definitive chemoradiation with weekly cisplatin (40 mg/m2) between November 2007 and April 2023. Adherence to weekly cisplatin was defined as receiving at least 5 cycles with a total cumulative dose of 200 mg/m2. Survival outcomes were evaluated using Kaplan-Meier method, log-rank tests, Cox proportional hazard multivariable (MVA) analyses. Logistic MVA was performed to identify variables associated with low adherence to weekly cisplatin. Fine-Gray MVA was performed to analyze failure outcomes with death as a competing event. Results Among 119 patients who met our criteria, 51 patients (42.9%) had low adherence to weekly cisplatin. Median follow up was 19.8 months (interquartile range 8.8-65.6). Low adherence to weekly cisplatin was associated with worse overall survival (adjusted hazards ratio [aHR] 2.94, 95% confidence interval [CI] 1.58-5.47, p < 0.001) and progression-free survival (aHR 2.32, 95% CI 1.29-4.17, p = 0.005). It was also associated with worse distant failure (aHR 4.55, 95% CI 1.19-17.3, p = 0.03), but not locoregional failure (aHR 1.61, 95% CI 0.46-5.58, p = 0.46). KPS < 90 was the only variable associated with low adherence to weekly cisplatin (adjusted odds ratio [aOR] 2.67, 95% CI 1.10-6.65, p = 0.03). Conclusion Our study suggested that over 40% of patients underwent fewer than 5 weekly cisplatin cycles and that low adherence to weekly cisplatin was an independent, adverse prognostic factor for worse survival and distant failure outcomes. Those with reduced adherence to weekly cisplatin were more likely to have poor performance status. Further studies are warranted to improve the adherence to chemotherapy and outcomes.