Non-functioning pituitary adenomas: indications for postoperative radiotherapy

OBJECTIVE To determine the indications for postoperative radiotherapy after surgical resection of a nonfunctioning pituitary macroadenoma. METHODS A retrospective chart review of 72 patients with histologically pro ven chromophobe adenoma who presented for pituitary surgery between January 1985 and June 1998, with a minimum follow-up period of 12 months. The stud y endpoint was tumour recurrence or progression detected either by routine follow-up imaging or by clinical progression with subsequent confirmation b y imaging. A proportional hazards model was used to determine independent p rognostic factors. RESULTS Mean follow-up was 64 months. In the radiotherapy group 13 of 50 re curred (or progressed) (26%), while in the nonradiotherapy group 10 of 22 r ecurred (46%), logrank test, P = 0.025. In patients assessed as having comp lete excision of tumour (n = 20) only two recurred (10%), both in patients without radiotherapy. No further treatment has been required in either case to date. In patients with residual tumour (n = 52), 41 had radiotherapy wi th 13 recurrences (32%), while 11 patients had no radiotherapy with eight s ubsequent recurrences (73%); logrank test, P = 0.007. Further treatment has been required in the majority of these cases, Cox's proportional hazards m odel analysis showed that only complete tumour removal and postoperative ra diotherapy were independent favourable prognostic factors. CONCLUSIONS The goal of surgery should be complete surgical excision where possible. The risk of recurrence in patients with no residual tumour on pos toperative imaging is low enough to justify withholding routine postoperati ve radiotherapy in this group. In patients with residual tumour, convention al external beam radiotherapy administered within 12 months of surgery is e ffective at reducing recurrence or progression.