RISK OF NEW PRIMARY-CANCER IN PATIENTS WITH OROPHARYNGEAL CANCER

The relative risk of subsequent cancers was evaluated for a total of 9 ,092 patients with lip and oropharyngeal cancer recorded between 1953 and 1989 in the nationwide Finnish Cancer Registry. The observed numbe rs of patients were compared with those expected on the basis of the i ncidence rates in the Finnish population. There were 1,130 patients (1 2%) with a new cancer. The standardised incidence ratio (SIR) of contr acting a new primary cancer was 1.2 for lip cancer patients (95% CI 1. 1-1.3) and 1.4 for patients with oropharyngeal cancer (95% CI 1.2-1.4) . Among lip cancer patients, a statistically significant excess risk w as found for subsequent cancers in the oropharyngeal area (SIR 1.9, 95 % CI 1.1-3.1), larynx (SIR 2.0, 95% CI 1.2-2.9) and lung (SIR 1.4, 95% CI 1.3-1.6), i.e. for cancers with tobacco aetiology. Among patients with oropharyngeal cancer there was an excess of lip cancer (SIR, 3.5, 95% CI 1.5-6.9), lung cancer (SIR 1.8, 95% CI 1.3-2.3) and leukaemia (SIR 2.3, 95% CI 1.0-4.3). Radiotherapy for the first primary did not increase the risk of new cancer.