Outcome of fractionated stereotactic radiotherapy in patients with pituitary adenomas resistant to conventional treatments: a 5.25-year follow-up study.

OBJECTIVE: To investigate the long-term outcome of fractionated stereotactic radiotherapy (FSRT) [45 Gy (range 45-54) in 25 fractions] in patients with pituitary adenomas characterized by tumour progression or hormonally active disease despite surgery and/or medical therapy.

DESIGN: This was an observational follow-up study of 5.25 years (median; range 1.7-10.4).

PATIENTS AND MEASUREMENTS: Pituitary tumour volume, visual acuity/fields, hypersecretion, hypopituitarism, cerebrovascular disease, second brain tumours and mortality were examined at regular intervals after FSRT in 30 patients with pituitary adenomas (20 nonfunctioning macroadenomas, 10 functioning). Prior to FSRT, 83% had been operated 1-3 times, 47% had visual field deficits/impaired vision and 50% pituitary dysfunction. Progressive disease, stable disease, partial and complete tumour response were defined by MRI.

RESULTS: Tumour growth control was 100%. At the end of follow-up, 30% had stable disease, 60% partial and 10% complete tumour response. Visual function was preserved and 36% of patients with prior field deficits improved. GH decreased from 4.2 (range, 2.3-6.5) to 1.1 (range, 0.5-1.5) microg/l (P < 0.001) in patients with acromegaly, and medical therapy could be reduced. In large prolactinomas, partial response or complete tumour response was achieved. FSRT was well tolerated. Pituitary function remained normal in 27%, 33% of patients had stable dysfunction, 17% deteriorated further and 23% developed new dysfunction. There were no cerebrovascular events, second brain tumours or FSRT-related deaths.

CONCLUSION: According to this long-term follow-up study, FSRT is an efficient and safe adjuvant therapy for pituitary adenomas refractory to conventional treatments.