Cancer risk following radiotherapy for infertility or menstrual disorders

A cohort of 968 Israeli women treated with radiotherapy for infertility was followed up for cancer incidence. The majority of the subjects were irradi ated to both the ovaries and the pituitary gland. Mean doses to the brain, colon, ovary and bone marrow were 0.8, 0.6, 1.0 and 0.4 Gy, respectively. M ore than 10 years after radiation treatment, 60 cancers were observed compa red with 74.5 expected based on national cancer incidence rates (standardiz ed incidence ratio 0.81, 95% confidence interval 0.61-1.04), No statistical ly significant excess or deficit was seen for any individual type of cancer ; however, a non-significant 60% increased risk of colon cancer was observe d. Risk of colon cancer was higher among women with 2 or more treatments an d increased with length of follow-up. A decreased risk of breast cancer was suggested. Neither age at exposure nor attained age modified subsequent ca ncer risk. No clear excess of any cancer site was observed among women at o rgan doses above the median compared with subjects at doses below the media n, except a slight increase in colon cancer. No significant excess incidenc e of cancer was demonstrated in this small cohort of patients treated with radiotherapy for infertility, Our results are consistent with those from an earlier study of cancer mortality among women receiving radiotherapy for i nfertility conducted in New York City. Published 1999 Wiley-Liss, Inc.dagge r.