Clinical characteristics, treatment methods and prognoses of patients with oral squamous cell carcinoma in Japanese population: a single institution retrospective cohort study

Background: The status of oral cancer therapy in elderly patients in Japan, where ageing is rapidly progressing, may serve as a model for other countries with similar demographics. There is controversy over what kind of treatment should be applied and how aggressively it should be applied to very elderly patients who have exceeded the average life expectancy. Given that 85 years is approximately the overall Japanese life expectancy at birth, we considered a threshold of 85 years and hypothesized that the prognosis of oral squamous cell carcinoma (SCC) patients aged ≥85 years was not inferior to that of those < 85 years. The aim of the present study was to investigate the clinical characteristics, treatment methods, and prognoses of Japanese oral SCC patients aged ≥85 years. Methods: A retrospective cohort study was performed. The data of patients with primary oral SCC (n = 358) from 2005 to 2018 in our institute were extracted from electronic medical records. A total of 358 patients with oral SCC were divided into two groups (≥85 years group [n = 26] and < 85 years group [n = 332]) based on the age threshold of 85 years at the first visit. Kaplan-Meier survival analyses and Cox proportional hazard models were used to analyse overall survival (OS) and hazard ratios (HRs) according to age group, treatment, and TNM classification. Results: There was no difference in the 5-year OS rate between the ≥85 years and < 85 years groups (80.8% vs. 82.2%, P = 0.359). This finding was the same in the operative (94.7% vs. 85.8%, P = 0.556) and non-operative (42.9% vs. 33.2%, P = 0.762) groups, indicating that age did not affect prognosis. Mortality was lower in the operative group than in the non-operative group (adjusted HR: 0.276, 95% CI: 0.156–0.489, P < 0.001), suggesting that surgery is a superior method. However, non-surgical treatment was selected at a higher rate in the ≥85 years group (26.9% vs. 11.1%, P = 0.028). Conclusions: This study suggests the prognosis of ≥85-year-old patients was not inferior to that of < 85-year-old patients. We recommend that surgery as the first choice treatment for ≥85-year-old patients with oral SCC who can tolerate surgery should be performed.