Relationship of irradiated bone marrow volume and neutropenia in patients undergoing concurrent chemoradiation therapy for cervical cancer

Introduction: Concurrent chemoradiation therapy (CCRT) is the standard of care in the management of cervical cancer (International Federation of Gynecology and Obstetrics [FIGO] 2008 Stages IB2-IVA). Apart from the myelotoxic effects of chemotherapy, irradiation of pelvic bone marrow (BM) in the radiation field, can also contribute to hematological toxicity. Objectives: We examined the relationship of irradiated BM volume and neutropenia in cervical cancer patients undergoing CCRT. Materials and Methods: This prospective study was conducted in a tertiary cancer center with a longitudinal study design. A total of 43 patients undergoing CCRT for cervical cancer were included. Using auto bone segmentation, the external contour of pelvic bones from L4 vertebral body to ischial tuberosities were delineated as BM. The volume of BM receiving 10, 20, 40, 50 Gy was calculated. Complete blood counts were done weekly to evaluate the neutropenia and were graded according to Common Terminology Criteria for Adverse Events, version 3.0. The risk of developing neutropenia was analyzed using logistic regression. Results: Twenty-seven patients (62.8%) received 5 cycles of chemotherapy, 14 patients (32.6%) received 4 cycles of chemotherapy and 2 patients (4.7%) received 3 cycles of chemotherapy. Overall, 22 patients (51.2%) experienced acute neutropenia. On multivariate analysis increased BM V50Gy had a statistically significantly odds of developing any grade of neutropenia (odds ratio [OR] =1.43; 95% confidence interval [CI], 1.03-1.97; P = 0.028). When comparing patients receiving BM V40Gy >= 40% with BM V40Gy <40% odds of any grade of neutropenia was increased (OR = 2.03; 95% CI, 0.55-7.42; P = 0.28). Moreover, when comparing patients receiving BM V50Gy >= 15% with BM V50Gy <15% odds of any grade of neutropenia was increased (OR = 2.13; 95% CI, 0.57-7.97; P = 0.26). Conclusions: High-dose irradiation to the larger volume of BM prevents compensatory hyperplasia which leads to neutropenia in patients undergoing CCRT for cervical cancer.