Endocrine Abstracts

The effects of cancer therapy on pituitary and thyroid function evolve over many years and therefore careful long term screening strategies are required. Knowledge of the initial cancer diagnosis, age at diagnosis, radiation field, radiation dose and duration of follow up can aid identification of survivors most at risk.

Cranial irradiation to the hypothalamic pituitary axis increases the risk of pituitary dysfunction. The most common pituitary hormone to be affected is growth hormone. The diagnosis of growth hormone deficiency may not be life long as biochemical criteria vary between childhood, late adolescence and adulthood. Retesting of growth hormone status is therefore recommended. Tests routinely used to diagnose growth hormone deficiency may have limitations in this group of patients. Other pituitary hormones are affected infrequently unless the tumour is involving hypothalamic pituitary axis.

Thyroid dysfunction is common in patients who have undergone either neck irradiation or bone marrow transplantation. Annual blood tests are essential to monitor for hypothyroidism. Radiation increases the risk of thyroid nodules which have a high incidence of malignancy compared with the general population. Some controversy surrounds the UK’s recommendation that initial screening for thyroid nodules should be by annual palpation alone rather than ultrasound. The majority of evidence suggests that thyroid malignancy as a consequence of cancer therapy responds similarly to that occurring de novo.