CANCER INCIDENCE AMONG 78,000 ASTHMATIC-PATIENTS

The risk of cancer was evaluated among 77 952 asthma patients with bro nchial asthma. The series was obtained through linkage of two register s: the Finnish Social Insurance Institution's file of asthma patients and the Finnish Cancer Registry. There was a significant excess risk o f lung cancer in both sexes, the standardized incidence ratio (SIR) be ing 1.32 among men and 1.66 among women. In women, the risk of cancer of the rectum was significantly increased (SIR 1.42), whereas the risk s of cancer of the corpus uteri and multiple myeloma were lower than e xpected (SIR 0.76 and 0.53, respectively). In men, the incidence of ca ncer of the larynx was significantly reduced (SIR 0.63) and that of th e bladder increased (SIR 1.25). When both sexes were combined, cancers of the colon (SIR 1.17) and rectum (SIR 1.28) also showed a significa ntly elevated risk. A reduction in risk was seen in stomach cancer (SI R 0.88) and lymphatic leukaemia (SIR 0.55). The increased lung cancer risk may be due to local inflammatory changes. It is possible that dif ferences in the immune system, e.g. natural killer cell activity, expl ain some of the reduced cancer risks.