MULTIPLE-SCLEROSIS AND CANCER IN NORWAY

Introduction - During the extended course of multiple sclerosis (MS) t here are ample opportunities for the patients to develop other illness es including cancer, a potential long-term complication of the immunos uppressive drug treatment in MS. Material and methods - A retrospectiv e cohort study was done to estimate the relative risk of cancer in a p opulation of MS-patients from three Norwegian counties by record linka ge with the Cancer Registry of Norway. The cohort comprised 1271 MS-pa tients, 530 men and 741 women, identified in five longitudinal populat ion-based incidence studies. The reporting of cancer cases has been co mpulsory in Norway since 1952. Results - We found 73 cancer cases (sta ndardized incidence ratio (SIR)=0.86, 95% CI 0.68-1.09). Mean follow-u p time was 18.4 years. A significant excess of breast cancers was obse rved (SIR = 1.70, 95% CI 1.05-2.60). A non-significant excess of cance r in the urinary tract was observed. No significantly increased risk i n hematologic and lymphatic malignancies or malignant brain tumors was observed. The incidence of cancer of the digestive organs was signifi cantly lower than expected (SIR = 0.51, 95% CI 0.24-0.93). Conclusion - Overall, the study indicates that an MS-patient is not at any unusua l risk for subsequent development of cancer compared to the normal pop ulation.