Study Suggests Proton Beam Therapy Effective for Functional Pituitary Adenomas

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Current treatment of pituitary tumors includes surgery, radiation therapy, medications or a combination of these therapies. If a patient opts for radiation therapy, intensity-modulated radiation therapy (IMRT), stereotactic radiation therapy or proton beam radiation therapy may be used.

A recent study published in the International Journal of Radiation Oncology assessed outcomes in patients after treatment with proton therapy for functional pituitary adenomas, with results suggesting that it may be effective for patients with these tumors.

The data showed that the 3-year biochemical complete response rate was 54% in 74 patients with Cushing’s disease, 63% in eight patients with Nelson’s syndrome, 26% in 50 patients with acromegaly and 22% in nine patients with prolactinomas. Researchers reported median times to achieving biochemical complete response of 32 months, 27 months, 62 months and 60 months, respectively, noting that time to complete response was shorter in patients with Cushing’s disease and Nelson’s syndrome vs. other types of functional pituitary tumors (P=.001).

Tumor control was high — 98% among 140 patients — at a median follow-up of 43 months, according to the data.

Risk for hypopituitarism was present, with a 3-year development rate of 45% and a 5-year development rate of 62%. Median time to development was 40 months, according to the data.

The researchers also found that larger radiosurgery target volume as a continuous variable predicted hypopituitarism (adjusted HR=1.3; P=.004).

Of those who had severe adverse outcomes, four experienced post-radiosurgery seizures.

Researchers reviewed data from 165 patients who underwent proton therapy from 1992 to 2012 — 14 of whom already underwent photon radiation therapy. Resection had been performed in all but three patients. Sufficient data were available for 144 patients. Median follow-up was 4.3 years.

More than 90% of patients received proton stereotactic radiosurgery while the rest underwent fractionated stereotactic proton therapy.

Proton Radiotherapy Beneficial for Pituitary Adenomas
Study Suggests Proton Beam Therapy Effective for Functional Pituitary Adenomas

Proton irradiation is an effective treatment for functional pituitary adenomas, and hypopituitarism remains the primary adverse effect.

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