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

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 tumors with 10-15-mm margins 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. IFRT was well tolerated in all patients, and acute toxicity ≥ grade 2 was not observed. One case of grade 3 abdominal pain was reported 10 months post-RT. The overall and complete response rates were 85.7% and 50%, respectively. After a median follow-up of 28 (range, 17-42) months, the median PFS was 7 months. The 2-year PFS rate was 39.3%. Six of the 16 patients who developed outfield disease progression after IFRT were 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.