Radiotherapy in the management of giant pituitary adenomas

Background and purpose: The description of giant pituitary adenoma is not c lear yet. In this study we tried to identify which adenomas can be defined as giant pituitary adenomas when tumor control and progression free surviva l (PFS) are taken as end points and we also tried to evaluate prognostic fa ctors other than tumor size. Materials and methods: Between January 1981 and December 1997, 74 patients with pituitary macroadenomas more than 2 cm in size were treated. Of these 30 had tumors of more than 4 cm, while 44 patients were with tumors of 2-4 cm. Two patients received primary radiotherapy, while 72 were treated posto peratively. In the postoperative group, 52 patients underwent immediate rad iotherapy after surgery and 20 were treated with irradiation after regrowth or progression of the tumor after initial surgery. The mean and median tum or doses were 5518 and 5425 cGy, respectively. Results: Overall primary tumor control rate was 84%. The local control rate s among patients with tumors more than 4 cm and among patients with tumors 2-4 cm after radiotherapy were 73 and 91%, respectively. PFS was 65% for pa tients who had a tumor size of more than 4 cm and 87% for the patients with tumor size of 2-4 cm (P = 0.09). Young age (<20) and tumors of unclassifie d histology were the bad prognostic factors. Six months after radiotherapy normalisation or improvement in hormonal hypersecretion and visual field an d acuity deficits were 82 and 63%, respectively. Conclusion: Tumors more than 4 cm in size may be more convenient for the de finition of 'giant pituitary adenoma' when tumor control and PFS are taken as the end points. (C) 1999 Elsevier Science Ireland Ltd. All rights reserv ed.