Endocrine Abstracts

Background: Radiotherapy is the mainstay of NPC (nasopharyngeal carcinoma) treatment and recently there is increased use of concurrent chemo-irradiation (CCRT) to improve survival. The irradiation field for NPC includes the base of skull, risking radiation damage to the hypothalamic–pituitary (HP) axis.

Aims: To evaluate the prevalence of HP dysfunction in NPC survivors post-irradiation and to compare the risk of developing HP dysfunction amongst patients who had CCRT versus radiotherapy alone.

Methods: We recruited 58 patients (33 males/25 females) with no known hormonal dysfunction, who completed radiotherapy for NPC more than 3 years ago. All patients had baseline cortisol, ACTH, GH, IGF1, fT₄, TSH, FSH, LH, oestradiol/testosterone and prolactin measured at 8am after an overnight fast. In addition 49 of the 58 patients underwent dynamic testing with the insulin tolerance test (ITT).

Results: All patients received a standard dose of external beam radiotherapy of 70 Gy to the posterior nasal space. 43 patients received concurrent chemo-irradiation while 15 had radiotherapy alone. Median age: 56 (48.75–63.25) years and median time post-irradiation 8 (6.0–11.25) years. Hypopituitarism was present in 84% of patients, 31% with involvement of a single axis, 29% with two axes, 18% with three axes and 6% with four axes. The prevalence of GH, corticotroph, gonadotroph, thyrotroph deficiency and hyperprolactinaemia was 80, 41, 19, 3 and 25% respectively. The development of HP dysfunction was significantly associated with the use of CCRT when compared with the radiotherapy alone group, OR: 14.57 (2.42–28.6), P=0.01.

Conclusion: HP dysfunction post-irradiation is widespread amongst NPC survivors with the most common being GH-deficiency. Radiation-induced damage appears to be profoundly increased with the use of radio-sensitising chemotherapy. As these endocrinopathies result in significant morbidity/mortality we recommend periodic assessment of pituitary function post-irradiation.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.