Efficacy and safety of radiotherapy in acromegaly

Transsphenoidal surgery remains the treatment of choice in acromegaly, yet 40-50% of patients require secondary forms of therapy such as radiation therapy (RT) and somatostatin analogues (SA). We undertook this study to evaluate the efficacy and safety of RT in acromegaly.

Forty patients with acromegaly treated with RT (mean dose, 52 Gy) after failed pituitary surgery between 1993 and 2007 were analyzed; all were clinically and biochemically active. Patients were evaluated with yearly hormonal measurements [basal and glucose-suppressed growth hormone (GH), IGF-1, thyroid-stimulating hormone (TSH), free T4, cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone or estradiol and prolactin (PRL)] and with magnetic resonance imaging every 2 years.

Mean age of patients was 52.9 ± 12.1 years and 85% were female. All subjects had been followed for 1 year, 75% for 3 years, 70% for 5 years and 35% for 10 years. The median basal GH level fell from a baseline of 8.8 ng/mL to 2.27 ng/mL at 5 years (p = 0.001) and to 1.88 ng/mL at 10 years (p = 0.001). A GH <1 ng/mL was achieved by 46% and 57% of the patients at 5 and 10 years of follow-up, respectively. The proportion of patients achieving a normal IGF-1 was 36% at 5 years and 43% at 10 years. Before RT, hypothyroidism, hypocortisolism and hypogonadism were present in 44%, 26% and 74% of patients, respectively. After 5 years of follow-up (n = 28), these figures increased to 51%, 41% and 79% and over a third of the group had panhypopituitarism. One patient developed optic neuritis and another patient was diagnosed with a meningioma 10 years after RT. No cerebrovascular events or deaths occurred.

RT is an effective, low-cost and reasonably safe means of controlling acromegalic activity, particularly useful in parts of the world where SA are not readily available.