Radiation Therapy for Recurrent or Residual Pituitary Macroadenoma Invading Extrasellar Structures

Abstract

Purpose: This study aimed to evaluate the efficacy of radiation therapy (RT) for recurrent or residual pituitary macroadenoma (PMA) invading extrasellar regions.Materials and Methods: Patients from 2000 to 2020 who received RT with conventional fractionation for recurrent or residual PMA were included. The patients were divided according to the type of tumor [functioning (fx) or non-fx] and the aim of RT (sal-vage RT alone, immediate postoperative RT, delayed postoperative RT). Local and biochemical failure-free rates (FFR) were cal-culated using the Kaplan-Meier method.Results: With a median follow up of 82 months (IQR; 42-132 months), 36 patients treated with conventional RT (total 45-54 Gy in 1.8 or 2 Gy per fraction) for recurrent or residual PMA were analyzed. The 10-year local FFRs after RT for non-fx and fx tumor were 100% and 74.4%, respectively (p=0.047). In the immediate postoperative RT group, the 10-year local FFR was 100%, which was higher than the 90% FFR for salvage RT alone or 80% FFR for the delayed postoperative RT group (overall p=0.043, immediate vs. salvage; p=0.312, immediate vs. delayed; p=0.072). The local FFR was compared according to size of tumor with a cut-off value of 4 cm, and there was no significant difference (10-year local FFR 100% vs. 84.7% for >4 cm vs. <4 cm, p=0.320). The extents of extrasellar re-gion invasion were not predictive of local failure after RT. We found no grade >= 3 acute toxicities or newly developed visual impair-ments as a late toxicity of RT.Conclusion: Conventional RT is safe and effective for the local control of recurrent or residual PMA. Our data suggest that immedi-ate postoperative RT can be beneficial in recurrent or residual PMA, although further studies to evaluate risk factors of treatment failure in terms of treatment and disease characteristics are required.