Assessment of pituitary function in patients with nasopharyngeal carcinoma: The effect of radiotherapy

Radiotherapy (RT) plays a very important role in nasopharyngeal carcinoma (NPC). The pituitary gland can be affected by radiation due to its proximity to the nasopharyngeal cavity. Our aim is to demonstrate the effect of radiotherapy given for NPC on anterior pituitary function with basal pituitary hormones and provocative tests. Patients with NPC that were treated with definitive chemoradioherapy were reviewed retrospectively. Serum ACTH, GH, PRL, FSH, LH, TSH and cortisol, DHEAS, IGF-1, E2, testosterone, fT3, fT4 levels were recorded to evaluate pituitary function. Insulin tolerance test was performed to investigate hypothalamic-pituitary-adrenal axis and GH -IGF-1 axis. Comparison between early tumor stage and advanced tumor stage for pituitary dysfunction was done. The median time interval between the RT and endocrinologic evaluation was 4.0 (1-13) years. ACTH deficiency was found to be most common hormonal problem with a frequency of 73.7%. Of these 71.4% were mild adrenal deficiencies. GH deficiency was seen in 60% of patients. fT3, TSH, GH and IGF-1 levels were significantly lower in patients with advanced tumor stage compared with early tumor stage (p = 0.033, p = 0.022, p = 0.043, p = 0.022, respectively). Growth hormone deficiency was found in all of advanced and in 43% of early tumor stage patients (p = 0.017). We found higher rates of ACTH and GH deficiencies followed by gonadotropin, corticotropin and thyrotropin deficiency. Basal pituitary hormones will not be sufficient to evaluate anterior pituitary failure. Annual and systematic dynamic tests together with basal anterior pituitary hormones would be needed.