Endocrine Abstracts

A 31 year old female presented to the Endocrine day ward due to headache and dizziness in 2015. She had a background of childhood acute lymphoblastic leukaemia diagnosed at age 7 treated with chemotherapy. She had a cerebral recurrence at age 10 and underwent cerebral radiotherapy, further chemotherapy and subsequently total body irradiation and bone marrow transplant. Following this treatment she was diagnosed with panhypopituitarism and required hormone replacement therapy with growth hormone, hydrocortisone, levothyroxine, oestrogen, progesterone and desmopressin. She reported severe headaches and dizziness with an episode of collapse, with similar episodes found to be secondary to hyponatraemia. She also reported changes in her right breast, with nipple inversion. On examination there was a mass palpable within the right breast and was referred to her local breast clinic. She was found to have breast cancer and underwent a right-sided mastectomy and axillary node clearance. Her oestrogen was stopped and was started on Letrozole. Her genetic screen was negative. She underwent a prophylactic left mastectomy which subsequently showed an invasive ductal carcinoma. She was advised to continue Letrozole. In 2022 she was found to be hypercalcaemic and following investigation found to have primary hyperparathyroidism. A bone density scan showed significant osteoporosis at the femoral head. She is currently undergoing imaging to guide surgical treatment of primary hyperparathyroidism given high risk of worsening bone health given her oestrogen deprived state. Our patient demonstrates several secondary effects of her childhood cancer treatment. Early on her management plan she received high dose whole brain irradiation. Cerebral irradiation has been long shown to lead to endocrine deficiencies with varying degrees of pituitary dysfunction secondary to the radiation field and the radiation dose. Growth hormone and gonadotrophins are the most sensitive to radiation with abnormalities in TSH and ACTH related to higher doses of radiation¹. The drop in gonadotrophins appears to be a major contributor in the high rates of osteoporosis in patients following childhood cranial irradiation.⁴ Total body irradiation is used in conditions such as lymphoma, leukaemia and multiple myeloma. It provides radiation to the entire body allowing penetration to areas that are often less accessed by chemotherapy². It is also used prior to stem cell transplantation. Following total body irradiation, patients are at 2.8 times higher risk of subsequent malignancy with the highest risk associated with the highest doses³. Surveillance programmes for childhood cancer survivors remain difficult given the wide variety of complications.