Incidence of second metachronous head and neck cancers: population-based outcomes over 25 years.

Objectives/hypothesis: The primary objective was to determine the incidence of second metachronous head and neck cancers (HNC) following an index HNC and estimate their overall survival.

Study Design: Retrospective cohort study.

Methods: A total of 1,658 consecutive primary HNC patients diagnosed in 1986 to 1990 were identified through the prospectively maintained provincial BC Cancer Registry database. They were followed up for a period of 25 years. Survival analysis and second cancer estimates were performed with standard Kaplan-Meier & Cox regression analysis.

Results: Out of a total of 443 (27%) second cancers, 89 (5%) second HNC occurred in 1,658 HNC patients, with an actuarial metachronous HNC incidence rate at 5, 10, 15, 20, and 25 years that was 3.9%, 8.1%, 10.4%, 13.2%, and 14.5%, respectively. Second primary cancer (SPC) in lung and esophagus occurred in 155 (9%) and 32 (2%) patients, respectively. The median follow-up time for all patients and alive patients was 4.05 years (range, 0.2-25.0 years) and 23.2 years (range, 20.76-25.0 years), respectively. Of second HNC, 83 (93%) were metachronous. Oral cavity (P < 0.001) and oropharyngeal (P < 0.002) index cancers were more likely to develop a metachronous HNC. The overall survival rate for the metachronous HNC patients at 5 years is 15%. SPCs in esophagus and lung had lower overall survival compared to second HNC (P < 0.001).

Conclusion: Oral cavity and oropharyngeal cancers carry the highest risk of a subsequent metachronous HNC. Given the incidence and prognosis of second HNC, future research should address the frequency and duration of screening the head and neck region for a second cancer.