Clinical characteristics of multiple primary carcinomas of the oral cavity

Summary Objectives This study aimed to clarify the clinical characteristics of multiple primary carcinomas of the oral cavity. Materials and methods We retrospectively reviewed the cases of 1015 patients who were treated during follow up for oral cancer at Tokyo Medical and Dental University between March 2001 and December 2012. We compared the clinical characteristics of 961 patients who developed single primary oral squamous cell carcinoma (SCC) during follow up and 54 patients who subsequently developed multiple primary carcinomas in the oral cavity. Results Mean age at first diagnosis was significantly higher in patients with multiple primary carcinomas than single primary carcinoma. Multiple primary carcinomas showed a female predilection, were most prevalent in the gingiva, and tended to show earlier tumor and nodal stages than single primary carcinoma. The local recurrence rate was higher for multiple primary carcinomas than single primary carcinoma, and it increased with the number of multiple primary occurrences. The disease-specific survival rate at 10 years for patients with single primary carcinoma was 85.3% and that for patients with multiple primary carcinomas was 79.6%. The cumulative incidence rate for metachronous second multiple primary carcinomas after the onset of first carcinoma at 10 years was 8.0%. The recurrence of multiple primary carcinomas did not decrease the survival rate. Conclusion Differences were found in the clinical characteristics between patients with single oral SCC and those with multiple primary oral carcinomas. Early diagnosis and treatment as well as close long-term follow up are needed for patients with multiple primary oral carcinomas.