Chemoradiotherapy for locally advanced squamous cell carcinoma of the oropharynx: Does completion of systemic therapy affect outcomes?

INTRODUCTION: Current standard of care for locally advanced squamous cell carcinoma of the oropharynx (LA-OPC) consists of concurrent chemoradiotherapy. Due to toxicities associated with this treatment, a significant portion of patients are unable to complete the systemic therapy portion of their treatment course. The impact of incomplete systemic therapy on patient outcomes remains unclear.

METHODS: Demographic, treatment, and outcome data were retrospectively collected for patients with LA-OPC treated definitively with concurrent chemoradiotherapy between 2007 and 2014. Overall and disease-free survivals were estimated via the Kaplan Meier method. Log rank test was used to compare distributions of survival amongst groups. Cox regression was utilized for all multivariate analyses. P values of <0.05 were considered statistically significant.

RESULTS: In total, 73 patients with LA-OPC were identified with a median follow-up of 3.4years. Concurrent systemic therapy regimens consisted of bolus cisplatin every 3weeks (76.7%), weekly cetuximab (20.5%) and weekly cisplatin (2.7%). Forty-three patients (58.9%) were able to complete the prescribed concurrent systemic regimens. Upon multivariate analyses, patients who did not complete systemic therapy were noted to have a non-significant trend towards increased distant failure (20.0% vs 7.0%, p=0.12). Additionally, patients who did not complete systemic therapy were noted to have a near significant trend towards increased risk of death (36.7% vs 17.9%, p=0.053).

CONCLUSIONS: These results suggest that completing systemic therapy may affect survival in patients undergoing definitive radiotherapy with concurrent systemic therapy for LA-OPC. Further, this data demonstrates that though local recurrences are not affected when planned systemic therapy cycles are omitted, the risk of distant failure may increase. These associations require further study to clarify the effect Incomplete systemic therapy has on outcomes for LA-OPC.