Genetic and teratogenic effects of cancer treatments on gametes and embryos

Male and female germ cells vary in their sensitivity to the mutagenic effec ts of chemotherapy and radiotherapy, depending on their stage of maturation and the agent used. Although sperm DNA damage exists following treatment, no increase in genetic defects or congenital malformations was detected amo ng children conceived to parents who have previously undergone chemotherapy or radiotherapy. The use of assisted reproductive technologies and microma nipulation techniques might increase this risk; hence caution should be exe rcised. In female cancer patients, miscarriage and congenital malformations are not increased following chemotherapy. However, when IVF and embryo cry opreservation is practised between or shortly after treatment, possible gen etic risks to the growing oocytes exist, and hence the babies should be scr eened. During pregnancy, the potential teratogenic effects of chemotherapy influence the choice and timing of therapy. Termination is usually recommen ded in the first trimester, Second- and third-trimester exposure does not u sually increase the teratogenic risk and cognitive development, but it may increase the risk of poor obstetric outcome and fetal myelosuppression. Dur ing the first two weeks after fertilization of the embryo, radiation is let hal but not teratogenic. High doses of radiation during pregnancy induce an omalies, impaired growth and mental retardation, and there may be an increa sed risk of childhood leukaemia and other tumours in the offspring.