Pelvic Bone Marrow Sparing Intensity Modulated Radiation Therapy Reduces the Bone Mineral Density Loss of Patients With Cervical Cancer.

Purpose: To test the efficacy and feasibility of pelvic bone marrow sparing intensity modulated radiation therapy (PBMS-IMRT) in reducing bone density loss for patients with cervical cancer undergoing pelvic radiation therapy (RT).

Methods and materials: Patients with nonsurgical cervical cancer with stage Ib2-IIIc cancer were randomly allocated into the PBMS group or the control group. The PBMS group additionally received pelvic bone marrow dose constraint. Computed tomography (CT) imaging sets were acquired at baseline and at 1, 3, 6, 9, and 12 months after treatment. Radiation dose and Hounsfield unit were registered. Bone density loss rates and fracture events at different follow-up time points were recorded.

Results: Data from 90 patients in the PBMS group and 86 patients in the control group were used for statistical analysis, which included 30 and 26 patients with extended-field radiation therapy (EFR), respectively. The median follow-up for all patients was 12 months. Compared with baseline, the bone density of all bones at the last follow-up decreased by 43% and 53% in the PBMS and control groups, respectively, with the most significant decline at 1 month after treatment. Although patients without EFR received minimal irradiation in the upper lumbar spine, a 22.33% decrease in bone density was detected. In the group of patients with EFR, the decrease was 51.18% (P < .01). Lumbar or pelvic fracture incidence rates of patients in the PBMS and control groups were 7.8% and 12.79%, respectively. Among the dosimetric parameters, mean dose had the strongest correlation with bone density loss.

Conclusions: In patients undergoing pelvic RT, the loss of bone density can begin to appear early after RT, and it can occur either inside or outside of the irradiation field. Results of this study showed that PBMS-IMRT reduced bone mineral density loss compared with IMRT alone.