A PROSPECTIVE-STUDY OF CANCER INCIDENCE IN A COHORT EXAMINED FOR ALLERGY

In order to assess the association between atopy and cancer risk, a co hort of 6593 skin-prick-tested patients was established. Among atopic subjects, no overall increased cancer risk was found, but the incidenc e of both breast cancer (standardized incidence ratio (SIR) 2.50, 95 % CI 1.01-5.16) and malignant lymphomas (SIR 4.40, 95% CI 1.20-11.3) wa s significantly enhanced. Atopic subjects with asthma showed a decreas ed overall cancer risk (SIR 0.73, 95% CI 0.27-1.60), as compared with the other asthmatic subjects (SIR 1.46, 95% CI 1.03-2.04). The cancer risk for subjects with rhinitis was near unity (SIR 1.11), irrespectiv e of whether the subjects were atopic or not. An almost significant ri sk increase for cancer was observed among subjects with urticaria (SIR 1.70, 95 % CI 0.99-2.80). Our results support neither the original hy pothesis of an overall cancer protective effect of atopy, nor that of an opposite effect; rather, they strengthen the view that the associat ion between atopic diseases and cancer is complex.