The choice of treatment after incomplete adenomectomy in acromegaly: proton--versus high voltage radiation.

The authors report the results of a study designed to compare the effectiveness of two different types of radiation in patients with acromegaly where surgical therapy had failed to normalize growth hormone (GH). Longterm follow-up after conventional high voltage radiation in 17 patients and proton therapy in 13 patients confirmed a similar reduction of GH levels in both groups. After 4.5 years a decrease of about 80% was achieved. After "conventional radiation" GH was normal in 8 (47%) and near normal in 6 (35%) while proton therapy resulted in normalization in 5 and improvement in 5 (38%). The slightly better results of "conventional radiation" must be attributed to lower pretreatment levels of GH. Side effects as additional pituitary deficits and oculomotor palsies were more often seen after proton treatment. Since the results of both radiation methods are similar and proton therapy has a tendency to more serious side effects we recommend "conventional radiation" as secondary treatment of acromegaly.