The Long-Term Effects of Postoperative Radiotherapy in Acromegaly: Results From a Single-Center Acromegaly Registry in Iran.

BACKGROUND

Acromegaly is a rare but severe condition characterized by the excessive secretion of growth hormone (GH), leading to various metabolic alterations. Treatment options include surgery, pharmacotherapy, and radiotherapy (RT). RT can control the disease biochemically, either alone or in conjunction with medical therapy. This study aimed to evaluate the effectiveness of conventional RT in patients with postoperative acromegaly over a 15-year follow-up period, using specific cutoff criteria.

METHODS

A retrospective analysis was performed on 55 acromegaly patients who were monitored for an average of 15 (13.3-16.7) years and treated with conventional RT (median dose of 52 Gy) following pituitary surgery. Hormonal assessments included baseline and glucose-suppressed GH and IGF-1 levels, and side effects associated with RT were evaluated.

RESULTS

The baseline GH level decreased from 20.7 (16-25.4) μg/L to 11.2 (8.3-14.1) μg/L (p < 0.001) at 2 years, further dropping to 5.8 (4.99-6.61) μg/L (p < 0.001) at 5 years, and to 2.2 (1.66-2.74) μg/L (p < 0.001) at 10 years after RT. Rates of patients achieving suppressed GH levels < 1 μg/L rose from 9% at 2 years to 25% at 5 years, 42% at 10 years, and 76% at 15 years. IGF-1 levels normalized in 5% of participants at 2 years, 14% at 5 years, 38% at 10 years, and 60% at 15 years. After 10 years, 78% of patients experienced hypogonadism, 80% experienced hypothyroidism, and 82% experienced hypocortisolism. Neurological complications were reported in 4% of patients 10 years post-RT, while 4% developed visual impairments and optic neuropathy within 5 years.

CONCLUSION

The results suggest that conventional RT is an effective long-term management strategy for patients who do not respond adequately to medical therapy or surgery. However, the high incidence of late-onset hypopituitarism must be taken into account.