Bone Marrow-Sparing Pelvic Radiotherapy: Clinical Evidence, Dosimetric Constraints, and Clinical Outcomes.

Pelvic radiotherapy is widely used in the treatment of several common malignancies but is frequently accompanied by hematologic toxicity due to incidental irradiation of active bone marrow within the pelvis. Growing interest has therefore focused on strategies aimed at reducing unnecessary marrow exposure while preserving target coverage and treatment effectiveness. This narrative review provides an overview of the biological basis of radiation-induced marrow injury, current approaches to bone marrow identification and sparing, and the clinical relevance of these strategies across major pelvic cancer sites. Available evidence suggests that limiting bone marrow irradiation can reduce treatment-related hematologic toxicity, particularly in patients receiving combined modality therapy, and may have implications for immune preservation. However, the extent to which marrow-sparing techniques influence long-term oncologic outcomes remains uncertain. Further prospective research is required to refine planning strategies and to better define the clinical role of bone marrow preservation in pelvic radiotherapy.