Intra-cavitary brachytherapy in endometrial carcinoma: experience with cobalt-60 source

Area of Science:

• Oncology
• Radiation Oncology
• Gynecologic Oncology

Background:

• Localized endometrial cancer treatment often involves surgery followed by adjuvant radiotherapy.
• High-dose-rate (HDR) brachytherapy, specifically vaginal cuff brachytherapy (VCB), is a key component of adjuvant treatment.
• The cobalt-60 (⁶⁰Co) isotope is an alternative source for HDR-VCB, necessitating evaluation of its dosimetric and clinical parameters.

Purpose of the Study:

• To report vaginal cuff brachytherapy (VCB) dosimetry parameters and clinical outcomes for localized endometrial cancer patients treated with adjuvant HDR brachytherapy.
• To evaluate the efficacy and safety of using a cobalt-60 (⁶⁰Co) source for adjuvant HDR-VCB.
• To compare outcomes with those previously reported using iridium-192 (¹⁹²Ir) sources.

Main Methods:

• Retrospective analysis of 93 patients with endometrial cancer treated with surgery and adjuvant VCB between 2011 and 2017.
• Analysis of dosimetry variables (D_2cc, D_1cc, D_0.1cc for OARs) and vaginal mucosa isodose lines.
• Evaluation of local relapse (LR), regional relapse (RR), distant metastasis (DM), progression-free survival (PFS), and overall survival (OS) using Kaplan-Meier analysis; toxicity assessed using Pearson r and multivariate regression.

Main Results:

• The study included 93 patients, with a median follow-up of 39 months. Three-year OS and PFS were 87.5% and 85.5%, respectively.
• Low rates of recurrence were observed: LR (2.2%), RR (7.5%), DM (12.9%).
• Mean rectal and bladder D_2cc/D_0.1cc were within acceptable limits. Most common acute toxicity was vaginal mucositis (8.9% ≥ G2); chronic toxicity included vaginal stenosis (25.3% ≥ G1).

Conclusions:

• Adjuvant HDR-VCB using a ⁶⁰Co source for endometrial cancer is well-tolerated.
• Clinical outcomes (survival, recurrence) and toxicity profiles are comparable to those reported with ¹⁹²Ir sources.
• ⁶⁰Co HDR-VCB is a viable and effective option for adjuvant treatment of localized endometrial cancer.