Sep 29

SS 41 - Optimizing Radiation Therapy in Gynecologic Cancers: Fractionation, Targeting, and Toxicity Reduction

326 - MRI-Guided Pelvic Active Bone Marrow-Sparing IMRT in Cervical Cancer: A Single-Center Prospective Randomized Controlled Trial

04:15pm - 04:25pm ET

Room 162

Presenter(s)

Fang Wu, MD - The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi

F. Wu¹, Z. Yang¹, T. Gao¹, W. Huang², Y. Bin³, and Y. Zhang¹; ¹Department of Radiation Oncology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China, ²Department of Radiation Oncology, First Affiliated Hospital of Guangxi Medical University,, Nanning, Guangxi, China, ³Department of Radiation Oncology, The First Affiliated Hospital of Guangxi Medical University, nanning, China

Purpose/Objective(s):

Numerous investigations have found a link between pelvic active bone marrow radiation dosage and acute hematopoietic toxicity (HT). Therefore, initial hematologic toxicity during radiotherapy can be reduced by restricting the radiation dose to pelvic active bone marrow. MRI can discriminate between the distribution of red and yellow marrow within the bone marrow cavity, which can be used to delineate active bone marrow. The purpose of this randomized controlled trial is to determine the efficacy of MRI-guided active bone marrow-sparing intensity-modulated radiation in minimizing HT during cervical cancer treatment.

Materials/Methods:

A total of 82 cervical cancer patients treated at the First Affiliated Hospital of Guangxi Medical University between February 2024 and December 2025 were enrolled and randomly assigned to either the bone marrow-sparing (BMS-IMRT) group or the traditional radiotherapy (IMRT) group. The BMS-IMRT group limited doses to hematopoietic active bone marrow with volume-dose limitations (V10 < 80%, V20 < 66%, V40 < 37%). The IMRT group did not place restrictions on hematopoietic active bone marrow. Both groups were given external beam radiation with 6MV X-ray intensity-modulated radiotherapy at a dose of 45-50 Gy/25f .At the same time, enrolled patients' peripheral blood T-lymphocyte and blood counts were assessed both before and after radiation treatment. Data was analyzed using statistical tools.

Results:

Clinical baseline characteristics did not significantly differ between the two groups of the 82 enrolled patients (40 in the BMS-IMRT group and 42 in the IMRT group). The BMS-IMRT group had lower V10, V20, and V40 values of active bone marrow in IMRT plans than the IMRT group (P<0.05). The incidence of grade 2 or higher leukopenia, neutropenia, and overall hematologic toxicity was reduced in the BMS-IMRT group versus the IMRT group (P=0.000, 0.000, 0.033). ROC curve research demonstrated that hematopoietic active bone marrow V10 and V20 were linked to HT2+ incidence, with appropriate cutoff values of 85.01% and 68.20%, respectively. Following radiation therapy, the BMS-IMRT group had greater CD4+ T cell counts, total T cell counts, and CD4/CD8 ratios than the IMRT group (P=0.008, 0.005, 0.010). There was no discernible difference between the two groups' incidence of acute adverse reactions (P > 0.05).

Conclusion:

Pelvic active bone marrow V10 and V20 in cervical cancer patients can predict the presence of HT2+. MRI can be used to identify pelvic hematopoietic active bone marrow and implement dose restrictions, which can successfully reduce the irradiation volume and dose of active bone marrow, reducing acute hematologic toxicity and the influence on CD4+ T lymphocyte numbers.