Endocrine Dysfunction in Patients with Nasopharyngeal Carcinoma after Radiotherapy -A Prospective Study with 10 Years Follow-Up

Abstract

Purpose: To investigate the late endocrine dysfunction in patients with nasopharyngeal carcinoma (NPC) following radiotherapy (RT). Materials & Methods: The endocrine function in 5 NPC patients (3 male and 2 female) treated with RT alone was analyzed in this study. Estimated doses to the hypothalamus, pituitary, and thyroid were 49.4-66.6 Gy, 50.9-70.2 Gy and 46.8 Gy, respectively. Growth hormone (GH), cortisol response to insulin tolerance test (In), thyroid-stimulating hormone (TSH) response to TRH and gonadotropin response to LHRH were measured before, at 1.5 years and at 10 years after RT. The basal levels of prolactin, estradiol or testosterone, total triiodothyronine, and thyroxine were also measured at these time points. Results: The pre-treatment endocrine function was normal in all patients. All of them developed GH deficiency and 2 patients with clinical symptoms of hypothyroidism had increased basal level of TSH at 10 years after RT. TSH responses to TRH were increased in 3 patients and delayed in 1 patient. One female patient developed amenorrhea and had decreased cortisol response to ITT. No hyperprolactinemia was observed in these patients. Conclusion: Endocrine dysfunction is a common complication in NPC patients following RT. The hypothalamic-pituitary region and thyroid gland should be shielded as much as possible if the possibility of cure is not compromised. Regular endocrine assessment and replacement of deficient hormone might be indicated in NPC patients following RT.