Radiation therapy for acromegaly?
Conventional radiation therapy of GH-secreting tumors causes a gradual decline in GH levels over many years, with maximal effect occurring at 10 to 15 years. Therefore, it is generally reserved as a third-line therapy for acromegaly. It may also increase the long-term risk of mortality. Stereotactic radiotherapy consists of applying a highly concentrated high-energy radiation therapy beam to the tumor and may be more effective and work more quickly than conventional radiation therapy for pituitary tumors. However, stereotactic radiotherapy still takes months to years to work. If radiation therapy is deemed necessary in acromegaly, stereotactic radiotherapy is generally preferred unless there is significant residual tumor, or the tumor is too close to the optic chiasm. Many patients eventually develop hypopituitarism from radiation therapy, and there may also be small risks of vision deficits, secondary tumors, cerebrovascular events, or cognitive effects.