Cancer risk following radiotherapy for infertility or menstrual disorders

Abstract

A cohort of 968 Israeli women treated with radiotherapy for infertility was followed up for cancer incidence. The majority of the subjects were irradiated 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. More than 10 years after radiation treatment, 60 cancers were observed compared with 74.5 expected based on national cancer incidence rates (standardized incidence ratio 0.81, 95% confidence interval 0.61-1.04). No statistically significant excess or deficit was seen for any individual type of cancer; however, a non-significant 60% increased risk of colon cancer was observed. Risk of colon cancer was higher among women with 2 or more treatments and increased with length of follow-up. A decreased risk of breast cancer was suggested. Neither age at exposure nor attained age modified subsequent cancer risk. No clear excess of any cancer site was observed among women at organ doses above the median compared with subjects at doses below the median, except a slight increase in colon cancer. No significant excess incidence 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 infertility conducted in New York City.