Objective To assess the effectiveness of pelvic bone marrow (PBM)-sparing intensity-modulated radiation therapy (IMRT) in mitigating acute hematologic toxicity (HT) in older patients with cervical cancer.

Methods A retrospective analysis of the data from 41 older patients with cervical cancer who underwent postoperative concurrent chemoradiotherapy (CCRT) between January 2015 and December 2016 at Tianjin Medical University Cancer Institute & Hospital was conducted. The patients were grouped into PBM sparing and non-PBM sparing groups. The HT grades, white blood cells, absolute neutrophils, hemoglobin, and nadir platelet count were assessed. In addition, the volumes of PBM with various radiation doses (V10, V20, V30, and V40) were calculated. Regression models with multiple independent predictors were used to examine the association between dosimetric parameters and HT.

Results The PBM sparing group exhibited a significantly lower incidence of HT and RT breaks than the non-PBM-sparing group. Decreased V20 and V40 were significantly correlated with lower rates of grades ≥2 and ≥3 leukopenia, respectively. A partitioning analysis identified a cutoff value of 61% for V20 of the whole pelvic bone to predict grade ≥2 leukopenia and 33.5% for V40 to predict grade ≥3 leukopenia.

Conclusions  PBM-sparing RT significantly reduced the incidence of acute HT and treatment breaks. Increased PBM V20 and V40 were associated with higher rates of grade ≥2 and grade ≥3 leukopenia, respectively.