There is a growing body of literature detailing the endocrine consequences of
cancer therapy. Certain conclusions can be drawn from the data presented. Patients who have received incidental hypothalamic--
pituitary gland irradiation need to be followed carefully with serial dynamic hormonal evaluations, as they are at high risk of developing
growth hormone and
prolactin abnormalities and can develop other pituitary tropic
hormone deficiencies as well. Children especially should be monitored closely as GH deficiency can be corrected if detected early. Patients who have received radiation to the head and neck region will need long-term (up to 30 years) surveillance for the development of
thyroid cancer,
hyperparathyroidism or
hypothyroidism. Persistent elevations of TSH after incidental thyroidal irradiation are frequently seen and should be reversed with
thyroid hormone administration in an attempt to minimize TSH stimulation of the irradiated gland. Radiation to the gonads will cause graded damage dependent on the dose delivered and the mode of fractionation. Age in a woman seems to be a significant factor of radiation sensitivity. Certain chemotherapeutic agents are radiomimetic in their gonadal effects; to date the
alkylating agents have been most commonly implicated. FSH elevations herald gonadal damage (
aspermia or loss of follicles) and should be looked for in patients receiving abdominal radiation or systemic
chemotherapy. Leydig cell dysfunction occurs less frequently. Of all the iatrogenic endocrine complications discussed, some are eminently treatable, and some are quite preventable. Greater awareness of the unexpectedly high incidence of hormonal dysfunction can help lessen
therapy-induced morbidity in long-term cancer survivors.