# Proton beam therapy as an effective treatment option for recurrent endometrial cancer

## TL;DR

Proton beam therapy shows promise as a safe and effective treatment for recurrent endometrial cancer, especially for smaller tumors.

## Contribution

This study evaluates proton beam therapy as a salvage treatment for recurrent endometrial cancer and identifies tumor size as a key predictor of success.

## Key findings

- Proton beam therapy achieved 80.2% and 68.8% local control at 1 and 2 years, respectively.
- Tumor size was the only significant predictor of local control, with smaller tumors (<22.5 mm) showing better outcomes.
- No grade ≥3 toxicities were observed in patients treated with proton beam therapy.

## Abstract

•Proton beam therapy achieved favorable local control with minimal toxicity in recurrent endometrial cancer.•Tumor size was the only significant predictor of local control, with smaller tumors showing better outcomes.•PBT may be a suitable salvage option, particularly for patients with limited-volume recurrence.

Proton beam therapy achieved favorable local control with minimal toxicity in recurrent endometrial cancer.

Tumor size was the only significant predictor of local control, with smaller tumors showing better outcomes.

PBT may be a suitable salvage option, particularly for patients with limited-volume recurrence.

To evaluate the efficacy and safety of proton beam therapy (PBT) for recurrent endometrial cancer (REC) and to identify predictors of local control (LC).

We retrospectively reviewed REC patients treated with PBT at our institution between 2008 and 2021. LC, progression-free survival (PFS), and overall survival (OS) were estimated using the Kaplan–Meier method, and prognostic factors were analyzed. Toxicities were graded according to CTCAE v5.0.

Nine patients with a total of 14 lesions were included (median follow-up, 36.4 months). The 1- and 2-year LC rates were 80.2 % and 68.8 %, respectively. Median PFS and OS were 13.6 and 36.4 months, respectively. Tumor size significantly influenced LC, with lesions < 22.5 mm showing superior outcomes. No grade ≥ 3 toxicities attributable to PBT were observed.

These findings suggest that PBT may be a safe and effective salvage treatment for REC, particularly in patients with smaller tumors.