**6. Conclusions**

Treatment of NPC with radiotherapy is associated with a high risk of radiation-induced hypothalamic-pituitary dysfunction. More than 80% of NPC survivors will have at least one anterior pituitary hormone deficiency and hyperprolactinaemia is frequently seen in women. Irradiation of the thyroid is associated with a significant risk of primary hypothyroidism. In the long-term there is increased risk of thyroid nodules and thyroid cancer, especially in children. These abnormalities in the endocrine functions are progressive and irreversible and can result in significant morbidity and impaired quality of life. In addition, chemotherapy may cause transient or permanent direct gonadal damage and hypogonadism. Regular endocrine surveillance is mandatory to achieve early detection of these abnormalities and timely treatment.
