ESTRO 2025 - Abstract Book

S879

Clinical - Gynaecology

ESTRO 2025

contribute to these complications (2,3). This study aims to investigate the relationship between bone marrow doses in these regions and the development of acute hematologic toxicities in patients undergoing chemoradiation with the VMAT technique on a Halcyon LINAC. Material/Methods: Patients with locally advanced cervical cancer (Stages IIA to IIIC2) were treated with chemoradiation using the VMAT technique on a Halcyon LINAC. Pelvic bones and the lumbar spine were contoured to assess the correlation between bone doses and acute hematologic toxicities. The Total Pelvic Bone (TPB), which includes para-aortic nodes, extends from L4 to the ischial tuberosity with the upper border at L1. The lumbar spine (LS) reaches the tip of the sacrum, and the lower pelvis (LP) spans from the femoral head to the ischial tuberosity. The iliac crest (IC) covers the iliac region. Dosimetric parameters, such as V5, V10, V20, V30, and V40, were used to evaluate the volume of bone receiving specific doses. Multilinear regression analysis was conducted to assess the relationship between bone marrow doses and acute hematologic toxicities. Results: A total of 82 patients were included who underwent treatment were included out of which 56 (68.3%) the patients were under 60 years old, and 26 (31.7%) were 60 or older. Among the cohort, 49 patients (59.8%) experienced anemia, while 23 patients (28%) developed neutropenia. Of these, 15 patients (18.3%) had Grade G2, 6 (7.3%) had Grade G3, and 2 (2.4%) had Grade G4 neutropenia. Thrombocytopenia was observed in 7 patients (8.5%), with 4 (4.9%) having Grade G2 and 3 (3.7%) having Grade G3.Higher radiation doses (P=0.042), cisplatin (P=0.003), and increased chemotherapy cycles (P<0.001) significantly associate with thrombocytopenia and neutropenia The (V5 and V10) in TPB (P=0.047), LP (P=0.042), and IC groups (P=0.001) were significantly associated with thrombocytopenia.