Radiation-related predictors of hematologic toxicity after concurrent chemoradiation for cervical cancer and implications for bone marrow-sparing pelvic IMRT.

PURPOSE: To determine factors predictive for hematologic toxicity (HT) associated with concurrent chemoradiation for Stage II through IV cervical cancer. METHODS AND MATERIALS: The medical records of 40 women receiving concurrent chemoradiation for cervical cancer were reviewed. Hematologic toxicity was defined by use of Common Terminology Criteria for Adverse Events (version 3.0). Variables predicting for HT including age, body mass index, transfusions, and bone marrow volumes irradiated were included in the data analysis. RESULTS: Of the patients, 13 (32.5%) had Grade 0 or 1 HT and 27 (67.5%) had Grade 2 through 4 HT (HT2+). Multiple logistic regression analysis of potential predictors showed that only the volume of bone receiving 20 Gy (V20) for whole pelvic bone tended toward significance for predicting HT2+. A strong correlation was noted between HT2+ and V20 (r = 0.8, p < 0.0001). A partitioning analysis to predict HT2+ showed a cutoff value of 79.42% (approximately 80%) for V20 of whole pelvic bone. That is, if the V20 of the whole pelvis exceeds 80%, the risk of HT2+ developing increases by a factor (odds ratio) of 4.5 (95%, confidence interval, 1.08-18.69) (p < 0.05). CONCLUSIONS: We have shown a correlation between bone marrow volume radiated and development of HT. This has implications for use of pelvic intensity-modulated radiation therapy, which can potentially decrease the volume of bone marrow radiated.