Objective  To summarize the clinical experience of intensity-modulated radiotherapy(IMRT) for patients with giant pituitary adenoma, and to provide evidence for clinical treatment.

  Methods  The data of patients with giant pituitary adenoma who received 6MV-X IMRT with linear accelerator (prescription dose of 56-60 Gy/28-30 fractions, 5 fractions per week) in the Department of Radiation Oncology of Peking Union Medical College Hospital from October 2012 to October 2018 were reviewed. Treatment outcomes were evaluated by the control rate of tumor growth, remission rate of endocrine hormone, and radiation-related complications.

  Results  A total of 15 patients were included in this study. There were 8 males and 7 females with a median age of 32 years. The control rate of tumor growth was 93.3% (partial response in 11 cases, stable in 3 cases, and development of pituitary carcinoma in 1 case). Among the 7 patients with functional giant pituitary adenoma, 1 patient achieved complete remission of the level of endocrine hormone and 2 patients achieved partial remission. Four patients treated with radiotherapy plus temozolomide achieved partial remission (median remission time was 5 months), and the remission rate and remission time were better than those who did not receive temozolomide. During the follow-up period after radiotherapy, 4 patients were found having newly pituitary dysfunction. There were no new or aggravating visional impairment and visual field defects.

  Conclusion  Intensity-modulated radiotherapy is an effective treatment for giant pituitary adenoma, which can reduce the tumor faster combined with temozolomide.