Effect of Pelvic Bone Marrow Sparing Intensity Modulated Radiation Therapy on Acute Hematologic Toxicity in Rectal Cancer Patients Undergoing Chemo-Radiotherapy

Abstract

BackgroundWhile chemo-radiotherapy improves local control in patients with locally advanced rectal cancer, it can also increase acute hematological toxicity (HT), which leads to poor outcomes. Patients receiving bone marrow radiation have been shown to develop acute HT. However, the safety and efficacy of bone marrow sparing is undetermined. The aim of our study was to explore the feasible dosimetric constraints for pelvic bone marrow (PBM) that can be widely used in rectal cancer patients undergoing chemo-radiotherapy.Methods112 rectal cancer patients were selected and divided into the PBM sparing IMRT group (60 cases) and the non-PBM sparing IMRT group (52 cases). All patients underwent pelvic radiotherapy with concurrent capecitabine-based chemotherapy. The PBM dosimetric constraints in the PBM sparing IMRT group were set to:V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%. An independent sample t test was applied for the dose-volume parameters, and Chi-squared analysis was applied for clinical parameters and adverse events.ResultsThe radiation dose to PBM (V5~V45, Dmean, P<0.05), PBM sub-regions (V10~V35, Dmean, P<0.05) and both femoral heads (V5~V40, Dmean, P<0.05) decreased significantly in the PBM sparing IMRT group compared with that of the non-PBM sparing IMRT group (P<0.05). There was no significant difference in any dose-volume parameters of the bladder and small bowel in either groups, and none in the planning target volume (PTV) dose homogeneity and conformity (P>0.05). For acute HT observation, the incidence of grade 3 acute HT (χ2 = 7.094, P=0.008) was significantly reduced in patients treated with PBM sparing IMRT compared with patients treated with non-PBM sparing IMRT. There was no statistical difference in the incidence of vomiting, diarrhea, fatigue, anorexia, nausea, hand-foot syndrome, cystitis, perianal pain and perianal dermatitis in patients of both groups (P >0.05).ConclusionsApplying PBM dosimetric constraints (V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%) can significantly reduce the radiation dose to PBM. The patients treated with PBM sparing IMRT had a lower incidence of acute HT compared with those treated with non-PBM sparing IMRT. Applying the PBM dosimetric constraints proposed by our study can benefits the patients with rectal cancer undergoing capecitabine-based chemo-radiotherapy.

Dosimetric and Hematologic Implications of Prostate-Only Versus Whole Pelvic Radiotherapy: Results of the Multicentric Phase 3 PROPER Study

“… 11 Also, for rectal cancer, a bone marrow-sparing approach appears to be beneficial and results in lower incidence of acute hematological toxicity. 23 In 2016, Cozzarini et al, already reported leukopenia and thrombocytopenia after postprostatectomy WPRT. 24 Recently, available literature on hematological toxicity after prostate radiotherapy was resumed within a systematic review.…”

A prospective comparative study on bladder volume measurement with portable ultrasound scanner and CT simulator in pelvic tumor radiotherapy

“…This protocol aligns with practices in other institutions. However, BV still exhibits significant variability during RT due to factors such as diet, water intake, and patient age [ 8 ]. To evaluate these differences, we analyzed the discrepancies in BV measured by PBSV3.2 and CT based on gender, treatment objectives (PR and RR), and age groups.…”

“…Bladder volume (BV) is a significant factor in determining the target volume for cervical/cervical cancer [ 3 , 4 ], prostate cancer [ 5 , 6 ], and rectal cancer [ 7 , 8 ]. Variations in BV among treatment fractions have been observed; Ahmad et al [ 4 ] found an average reduction of 71% in bladder capacity among patients with cervical cancer.…”

Development of a consensus-based delineation guideline for locally recurrent rectal cancer

“…A future priority in treatment planning may be bone-marrow sparing, as data in primary rectal cancer show that CRT can cause hematological toxicity, leading to dose reductions or treatment interruptions that are associated with worse oncological outcomes. [36,37] However, these findings have not yet translated to clinical practice in the form of constraints.…”