External beam radiation therapy radiation therapy in pituitary adenoma results in excellent local tumor control rates and improvements in excessive hormonal secretion. However, the safety of postoperative radiation therapy has been questioned in particular because of concerns related to possible long-term radiation-induced side effects, although serious late complications of radiation therapy are uncommon in pituitary adenoma patients. However, these concerns are often used to delay or reject radiation therapy.
The main aim of this thesis was to assess and compare several long-term side effects of conventional radiation therapy (i.e. incidence of second tumors, stroke, mortality, and radiological brain abnormalities, effects on cognition, and sexual function as aspect of quality of life) in pituitary adenoma patients treated with surgery and postoperative radiation therapy versus surgery alone and with a population without pituitary adenoma disease (i.e. the reference population).
None of our observational studies shows significant differences in long-term side-effects between pituitary adenoma patients treated with radiation therapy and surgery alone. However, the decision to treat with postoperative radiation therapy is based on a careful assessment of the balance of benefits and risks in the individual pituitary adenoma patient. The risk of serious radiation-induced long-term side effects is low with the radiation therapy techniques applied in the last decades and is expected to be lower with modern and more advanced radiation therapy techniques. Therefore, in most pituitary adenoma patients with otherwise uncontrolled disease, the benefits of postoperative radiation therapy outweighs the absolute small risk of serious side-effects.