Hypopituitarism after radiotherapy for extracranial head and neck cancers.

Background: The purpose of this study was to investigate the incidence of radiotherapy-induced primary and secondary hypopituitarism.

Methods: Three hundred twelve patients treated with radiotherapy for extracranial head and neck tumors between 1964 and 2000 were evaluated. Radiotherapy doses to the hypothalamus and pituitary were estimated by reconstructing treatment plans.

Results: Clinical hypopituitarism was observed in 44 (14.1%) patients after a median interval of 5.6 years. Hypothalamic dysfunction was reported in 14 patients after a median interval of 4.4 years. Neither fractionation nor adjuvant chemotherapy significantly impacted clinical hypopituitarism on multivariate analysis, but total dose to the pituitary was significant (p = .0228). Twenty-three of 68 (33.8%) patients tested for hypopituitarism demonstrated subclinical hypopituitarism. The 5- and 10-year rates of freedom from clinical hypopituitarism were 93% and 72%. The 5- and 10-year rates of freedom from subclinical hypopituitarism were 85% and 65%.

Conclusion: Clinical and subclinical manifestations of late radiation toxicity were observed in the hypothalamic-pituitary axis.