Involved-field radiation therapy for recurrent ovarian cancer: Results of a multi-institutional prospective phase II trial

Abstract

Objective. To evaluate the efficacy and safety of involved-field radiation therapy (IFRT) in patients with locoregionally confined recurrent or persistent epithelial ovarian cancer.

Methods. This study included patients with recurrent epithelial ovarian cancer eligible for IFRT either during diagnosis of the recurrence or after salvage therapies. IFRT was performed at a dose of ≥45 Gy for all tumorswith 10–15-mmmargins as seen on standard imaging. The primary endpoint was progression-free survival (PFS); the secondary endpoints were safety, response rate, local control, and overall survival (OS).

Results. Thirty patients with a mean number of 5.7 metastatic lesions each were enrolled between 2014 and 2016. Seventeen were treated with 3-D conformal radiation therapy (RT) and 13 with intensity-modulated RT. IFRTwaswell tolerated in all patients, and acute toxicity ≥ grade 2was not observed. One case of grade 3 abdominal painwas reported 10months post-RT. The overall and complete response rateswere 85.7% and 50%, respectively.After amedian follow-up of 28 (range, 17–42)months, themedian PFS was 7 months. The 2-year PFS rate was 39.3%. Six of the 16 patientswho developed outfield disease progression after IFRTwere successfully treated with repeat IFRT as salvage treatment. The 3-year local control and OS rates were 84.4% and 55.8%, respectively.

Conclusions. Although the primary endpoint was not met, IFRT might be safe and effective for in-field tumor control in patients with persistent epithelial ovarian cancer with a limited number of metastatic foci.We plan to conduct a larger scale multi-center phase II prospective study.