The role of radiation therapy after surgical resection of nonfunctional pituitary macroadenomas.

OBJECTIVE: Radiotherapy after aggressive surgical resection of nonfunctional macroadenoma (NFA) of the pituitary remains controversial. Historically, immediate postoperative radiotherapy has been recommended to decrease risk of recurrence. With the availability of high-resolution imaging, most neurosurgeons now withhold radiation until recurrence. There is relatively little evidence to support this practice, however. This study reviews postoperative results in a large number of patients with NFA, the majority of whom did not undergo prophylactic radiation.

METHODS: Of the 258 patients who underwent surgery from 1979 to 1999 for NFA, medical records were available for 176. Forty-four patients were treated with immediate postoperative radiotherapy after tumor resection, and the remaining 132 patients were followed up with serial imaging studies and treated with radiotherapy only when a recurrence was documented by follow-up imaging.

RESULTS: Patients in the group that received immediate postoperative radiotherapy at time of initial diagnosis and surgery did not differ significantly with respect to age or sex from those in the group that was observed. Five- and 10-year recurrence rates were 2.3 and 2.3%, respectively, for patients who received immediate postoperative radiotherapy, as compared with 15.2 and 50.5%, respectively, for patients who were followed up and did not receive radiotherapy unless there was evidence of recurrence or progression. No patient had symptomatic recurrence in the group that was observed if consistent follow-up was performed. Of the 26 patients who received radiotherapy at time of tumor recurrence or progression, 18 had adequate follow-up, and in all cases, the tumors either remained stable or regressed.

CONCLUSION: Withholding radiotherapy after a high-percentage resection of NFA leads to a higher recurrence rate, but it avoids exposing all patients to the risks of radiation. Deferring radiotherapy for patients with complete or near-complete resection seems to be a safe and prudent approach, as our data suggest that recurrences may be detected early with high-resolution imaging and treated effectively with radiation at time of recurrence. Therefore, immediate postoperative radiotherapy may be eliminated for patients with complete or near complete resection of NFA and who agree to undergo close follow-up for a long period.