Genetic counseling of the cancer survivor.

Each year, tens of thousands of persons are diagnosed with cancer, are treated, and become survivors while still in their reproductive years. Their concerns about possible germ-cell damage as a result of life-saving radiation, chemotherapy, or both are plausible, based on evidence from animal models and from somatic cell mutations in human beings. A 40-year follow-up of survivors of the atomic bomb blasts in Japan showed no detectable genetic damage and suggested that the human gonad is more resistant to radiogenic mutation than the laboratory mouse. The pooled results of studying 12 series of offspring of cancer patients showed a 4% rate of major birth defects (similar to that of the general population) and an excess of fetal loss and low birth weight in offspring of women who received abdominal radiotherapy. According to preliminary evaluation of a new National Cancer Institute collaboration with five cancer registries, offspring of survivors of childhood cancers had no more birth defects than expected and, beyond an increase in probably familial cancers in children younger than 5, no overall increase in childhood cancer. Ideally, genetic and reproductive counseling should take place as soon as cancer is diagnosed (before therapy starts) and again when pregnancy is contemplated.