Clinical and Translational Radiation Oncology (May 2025)
Correlation between radiation dose to bone marrow subregions and acute hematologic toxicity inendometrial cancer treated with external beam radiotherapy
Abstract
Aim: To identify dosimetric parameters associated with acute hematologic toxicity (HT) in endometrial cancer treated with volumetric modulated arc therapy (VMAT-RT). Methods: Patients with uterine adenocarcinoma treated in our Institution from March 2019 to November 2022 were retrospectively enrolled in this study. All patients underwent adjuvant external beam radiotherapy with Volumetric modulated arc therapy (VMAT) strategy plus a brachytherapy boost on vaginal cuff. When indicated, adjuvant platin-based chemotherapy was administered after surgery in upfront or sandwich setting. Pelvic bone marrow was contoured for each patient and divided into three subsites: lumbosacral spine (LSBM), ilium (IBM) and lower pelvis (LPBM). The volume of each region receiving 10,20,30 and 40 Gy (V10, V20, V30, V40, respectively) and mean dose (Dmean) was collected. Hematological toxicity during radiotherapy treatment was graded according to the CTCAE V 5.0. Linear logistic regression models were used to test associations between dosimetric parameters and HT. Results: Data from 99 patients were retrospectively analyzed. Adjuvant external beam radiotherapy was delivered to the pelvis with Volumetric modulated arc therapy (VAMT) strategy for a total dose of 45 Gy, 1.8 Gy/fraction plus a brachytherapy boost on vaginal cuff for a total dose of 10 Gy in 2 fractions weekly. Thirty-one patients developed during radiotherapy treatment an HT ≥ grade 2.With a sensitivity of 83.3 % and specificity of 61.5 %, V20 Gy LSBM 64 %) seems to be associated with HT in younger patients; instead in older than 70 patients the percentage of V20Gy LSBM seems not correlate with risk of toxicity. Future investigations should seek to confirm these findings through the inclusion of these parameters in the planning process.
