Can dosimetric parameters predict acute hematologic toxicity in rectal cancer patients treated with intensity-modulated pelvic radiotherapy?

Abstract

BackgroundTo identify dosimetric parameters associated with acute hematologic toxicity (HT) in rectal cancer patients undergoing concurrent chemotherapy and intensity-modulated pelvic radiotherapy.MethodsNinety-three rectal cancer patients receiving concurrent capecitabine and pelvic intensity-modulated radiation therapy (IMRT) were analyzed. Pelvic bone marrow (PBM) was contoured for each patient and divided into three subsites: lumbosacral spine (LSS), ilium, and lower pelvis (LP). The volume of each site receiving 5–40 Gy (V 5, V10, V15, V20, V30, and V40, respectively) as well as patient baseline clinical characteristics was calculated. The endpoint for hematologic toxicity was grade ≥ 2 (HT2+) leukopenia, neutropenia, anemia or thrombocytopenia. Logistic regression was used to analyze correlation between dosimetric parameters and grade ≥ 2 hematologic toxicity.ResultsTwenty-four in ninety-three patients experienced grade ≥ 2 hematologic toxicity. Only the dosimetric parameter V40 of lumbosacral spine was correlated with grade ≥ 2 hematologic toxicity. Increased pelvic lumbosacral spine V40 (LSS-V40) was associated with an increased grade ≥ 2 hematologic toxicity (p = 0.041). Patients with LSS-V40 ≥ 60 % had higher rates of grade ≥ 2 hematologic toxicity than did patients with lumbosacral spine V40 < 60 % (38.3 %, 18/47 vs.13 %, 6/46, p =0.005). On univariate and multivariate logistic regression analysis, lumbosacral spine V40 and gender was also the variable associated with grade ≥ 2 hematologic toxicity. Female patients were observed more likely to have grade ≥ 2 hematologic toxicity than male ones (46.9 %, 15/32 vs 14.8 %, 9/61, p =0.001).ConclusionsLumbosacral spine -V40 was associated with clinically significant grade ≥ 2 hematologic toxicity. Keeping the lumbosacral spine -V40 < 60 % was associated with a 13 % risk of grade ≥ 2 hematologic toxicity in rectal cancer patients undergoing concurrent chemoradiotherapy.

Bone marrow sparing RT in era of immunotherapy

“…Approximately half (40-50%) of bone marrow is localized in pelvic region [47,48]. Majority of available clinical data describes the application of intensity modulated radiation therapy (IMRT) for BMS-RT for prostate, cervical, rectum, anal cancers [47,[49][50][51][52][53][54][55][56][57][58]. In macroscopic cervical and rectum cancer dynamic irradiation techniques are still not first-line treatment options due to concerns over internal organ motion [8,9,59].…”

“…In CRT for rectal cancer Yang et al showed that patients with coxal (bilateral ilium, ischium and pubic) BM-V45 and sacral BM-V45 experienced lower WBC and ANC nadirs [53]. In another paper, Wan et al indicated that lumbosacral BM-V40 predicted grade ≤ 2 HT in CRT for rectal cancer [54]. In the study including 100 women, Chang et al noted that IMRT was superior to 3-D RT in medium and high doses (BM-V20, BM-V30, BM-V40) and mean BM dose [55].…”

Dose to specific subregions of pelvic bone marrow defined with FDG-PET as a predictor of hematologic nadirs during concomitant chemoradiation in anal cancer patients

“…Hence, selective sparing of pelvic osseous structures may be a viable option to decrease HT during concomitant CH-RT in anal cancer patients [9]. In several studies, a significant correlation between different dose-volume metrics and blood cell nadirs and/or HT was found [10][11][12][13][14][15]. Other than anal cancer, different clinical contexts were investigated such as cervical, rectal, lung and prostate cancer.…”

Dosimetric analysis and comparison of reduced longitudinal cranial margins of VMAT-IMRT of rectal cancer

“…In 50 patients treated with IMRT, a higher V20 of the pelvic bone marrow was associated with lower white blood cell nadir ( p = 0.048) and patients with V40 ≥ 41% of the lumbo-sacral bone marrow had higher risk to develop ≥Grade 3 hematologic toxicity [ 26 ]. The most comparable study design was from Wan et al [ 27 ]. Here the V40 of the lumbosacral spine was associated with clinically significant grade ≥ 2 hematologic toxicity in patients receiving conventional concurrent CRT (50 à 2 Gy, IMRT, Capecitabine) (grade ≥ 2hematologic toxicity with V40 ≥ 60% vs. V40 < 60% was 38.3% vs.13%, p = 0.005).…”