Efficacy and safety of induction chemotherapy in oral cavity cancer: An eight-year experience at a Portuguese reference center

Background: Induction chemotherapy has been described as an option in locally advanced oral cavity squamous cell carcinoma when the surgical morbidity is expected to be high. This work aimed to evaluate the outcome and safety of induction chemotherapy in this setting. Methods: We performed a retrospective and observational study including patients with oral cavity squamous cell carcinoma, treated with induction chemotherapy between January 2010 and December 2018. Outcomes included induction chemotherapy toxicity, treatment response, disease-free survival and overall survival. Results: A total of 108 oral cavity squamous cell carcinoma patients were included. Ninety-six (88.9%) had stage IV disease, while 12 (11.1%) had stage III. Eighty-four patients (80.8%) achieved at least a partial response to induction chemotherapy at clinical evaluation, and 75 (72.1%) at radiological evaluation. Seventy-eight patients have been proposed for subsequent definitive treatments, with no differences obtained in prognosis, when comparing surgical to non-surgical approaches. In patients treated with definitive treatments, improved five-year disease-free survival was obtained if at least a clinical (56.3%; p=0.001) or radiological (52.9%; p=0.001) partial response was achieved after induction chemotherapy. Similarly, superior five-year overall survival was verified for those achieving at least clinical (51.1%; p<0.0001) or radiological (52.6%; p=0.001) partial response. Also, accomplishing a pathologic complete response (n=22.6%) significantly improved disease-free survival (p=0.039) and overall survival (p=0.005). Grade 3 and 4 toxicities were observed in 52 patients (41.8%). Conclusion: Responses to induction chemotherapy predicted prognosis in our population, however important toxicities were observed. Further studies are necessary to identify induction chemotherapy response predictors and subgroups who may benefit from this approach.