The purpose of the study, presented in Chapter 2, was to demonstrate the benefit of immediate postoperative radiation therapy in residual non-functioning pitui-tary adenoma in perspective to the need for hormonal substitution and life expectancy. A retrospective cohort analysis was performed of 104 patients with residual NFA after surgery, operated in the time period 1979-1998 at the University Medical Center Groningen. Recurrence was defined as regrowth on computed tomography or magnetic resonance imaging. The occurrence of hormonal deficiencies was defined as the initiation of hormonal substitution therapy.
Seventy-six patients with residual NFA received immediate postoperative radia-tion therapy. In these patients local control was 95% after 10 years. Twenty-eight patients with residual NFA after surgery were followed with a wait-and-see
po-licy. In this group, local control was achieved in 49% of the patients after 5 years and in 22% after 10 years. Thus, the difference in local control in favour of imme-diate postoperative radiation therapy amounted to 46% and to 73% after 5 and 10 years, respectively. The majority of the patients in the wait-and-see policy group in whom a local recurrence developed received salvage radiation therapy, most frequently after re-operation. The median time interval between first surgery and radiation therapy was 38 months. Immediate postoperative radiation therapy and salvage radiation therapy at recurrence were similar in regard to technique, daily (1.8-2 Gray) and total dose (45-50 Gray) applied.
At present it is often assumed that immediate postoperative radiation therapy in case of residual pituitary adenoma adversely affects the development of hypopi-tuitarism as compared with a wait-and-see policy. The results from our retrospective study suggest that this assumption may need modification: preoperatively, directly after first surgery and at the end of follow-up no differences in favour of the patients with a wait-and-see policy were found regarding the need for thyroid-, glucocorticoid- and sex-hormone substitution. Also the number of hormone deficiencies per patient over time was not different between the two groups.
From our analysis it is likely that the supposed increased frequency of pituitary insufficiency attributable due to the immediate postoperative radiation therapy is counterbalanced by a high local recurrence rate, which necessitates re-operation as well as radiation therapy in the majority of patients. Moreover, overall survival in patients with residual NFA was found to be similar in the wait-and-see policy group compared to those patients who received immediate postoperative radiation therapy. Also in both groups of patients, life expectancy did not differ from that in the general population. Our results, therefore, do not support the opinion that it is advantageous to postpone radiation therapy in case of residual non-functioning pituitary adenoma. However, it is also noteworthy that our study demonstrated that in 15 patients with a completely resected non-functioning pituitary adenoma, local control rate after 10 years was as high as 95% with surgery alone. Therefore, routine use of postoperative radiation therapy is not justified for all pituitary adenomas.