Bone Marrow Toxicity clinical trials

The Effect of Bone Marrow-sparing Intensity-Modulated Radiotherapy to GI Cancer

Concurrent chemotherapy with external beam radiotherapy is the standard treatment of bulky or locally advanced cervical cancer, gastric cancer and rectal cancer.Despite excellent therapeutic results, acute hematologic toxicity (HT) is common with this regimen. Previous studies have founded acute HT was significantly associated the volume of pelvic (PBM) and lumbosacral bone marrow (LSBM) receiving 10 and 20 Gy radiation (RT). Therefore, reducing the volume of BM receiving low-dose RT might prevent HT. More than one-half of the body's bone marrow (BM) is located in the PBM, LSBM and proximal, where is just in the low dose of RT in patients with gastric, rectal and cervical cancer. Previous study have demonstrated highly conformal IMRT treatment plans reduced the volume of PBM irradiated resulting in less HT. We have since assumed that even better BM sparing is possible when the BM is entered as a separate constraint in the planning process. However, it is well known that hematopoietically active (red) BM is poorly visualized with computed tomography (CT). Consequently, the entire contents of the medullary canals must be entered as BM. Yet, a considerable portion of the medullary canal is comprised of inactive (yellow) marrow, which is composed primarily of fat. Contouring the entire medullary canals on CT thus overestimates the volume of active BM, unnecessarily constraining the IMRT plan. An alternative approach is the incorporation of functional BM imaging into the treatment planning process. One economical and efficiency approach involves the use of T1-weighted magnetic resonance (MR) images. Therefore, we designed this study to test whether a separate constraint of active BM identified by MR could reduce acute HT in course of concurrent chemoradiotherapy for patients with gastric and rectal cancer.