Late endocrine effects after treatment for nasopharyngeal cancer
HK Gleeson1, L Turnbull1, A Jostel1, A Donne2, AJ Sykes2, NJ Slevin2 & SM Shalet1
Endocrine sequelae occur following cancer therapy. The majority of studies focus on childhood survivors of common cancers, in particular brain tumours, and isolated growth hormone deficiency (GHD) following radiotherapy is well recognised. The need for endocrine follow up in adults or following treatment of less common cancers with lower survival rates is often overlooked. Survival following treatment for nasopharyngeal cancer is improving. Although therapy options are changing, the doses of radiation received by the pituitary far exceed those following the treatment of brain tumours. Therefore we have initiated endocrine screening of all patients treated for nasopharyngeal cancer.
40 patients (23 male) were identified. Baseline endocrine investigations were performed in all and 37 patients underwent endocrine stimulation tests.
Age at diagnosis was 52 (10-82) median (range) years and length of follow up was 6 (1-14) years. Biological effective dose of irradiation (BED) to the pituitary gland was 89 (0-183) Gy, and in 10 patients the irradiation field also involved the hypothalamus, 60 (49-110) Gy. 27 patients had chemotherapy.
16/37 (43%) patients had varying degrees of GHD (10 (27%) severe GHD; 7/39 (18%) had impairment of the hypothalamic pituitary adrenal axis (HPA) (6/7 patients with GHD); 4/40 (10%) and 3/40 (7%) had evidence of secondary hypogonadism and hypothyroidism respectively (all patients had severe GHD; 4 had impairment of HPA); 7 had raised prolactin levels (3>1000mU/L) (6 with GHD).
Patients with GHD had a similar duration of follow up (5 years), a higher BED to the pituitary (110 vs 60 Gy, p<0.01) and were more likely to have had hypothalamic irradiation (37 vs 19%) compared to those with normal GH status.
Once adequately replaced with hydrocortisone, sex steroid and thyroxine 8/10 patients with severe GHD have opted for GH replacement due to reduced quality of life.
Due to the high doses of irradiation to the pituitary in patients with nasopharyngeal cancer extensive pituitary hormone deficiencies occur. Endocrine screening and subsequent hormone replacement is essential to reduce morbidity.