Gastrointestinal Cancer

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SU_5_2048 - Clinical Study of Bone Marrow-Sparing Neoadjuvant Chemoradiotherapy for Rectal Cancer

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Clinical Study of Bone Marrow-Sparing Neoadjuvant Chemoradiotherapy for Rectal Cancer
Y. Wang, D. Yu, and B. Zhang; Jiangsu Province Hospital of TCM, Affiliated Hospital of Nanjing University of TCM, Nanjing, China

Purpose/Objective(s): To investigate bone marrow-sparing IMRT (BMS-IMRT) as a mean of reducing the volume of pelvic hematopoietic bone marrow (BM) irradiated and thus the risk of acute hematologic toxicity in LARC patients undergoing neoadjuvant chemoradiotherapy.

Materials/Methods: A prospective study was conducted to evaluate acute hematologic toxicity and clinical outcomes in eligible patients. The patients were divided into BMS-IMRT group and IMRT group randomly. The neoadjuvant therapy regimen included IMRT (95 %PTV 50Gy/25f, 2Gy/f/d, Monday to Friday), with concurrent chemotherapy (capecitabine 1650mg/m2, twice a day, Monday to Friday). Pelvic MRI was incorporated in the planning process to aid in the delineation of active BM on simulation CT imaging for all the patients but limitation dose of BM were carried out (V5<95%, V10<90%, V20<75%, V30<60%, V40<40%)only in BMS-IMRT group.

Results: Sixty patients were enrolled and divided into two 30-case groups, BMS-IMRT group and IMRT group randomly. Treatment was completed in 59 patients, as only 1 patient stopped chemotherapy due to acute Grade 4 leukopenia in IMRT group. BMS-IMRT group had an advantage over IMRT in terms of CI(P<0.05) but was inferior to IMRT for HI(P<0.05).BM-V10 and V20 in BMS-IMRT group were (80.52 ±9.18)% and (63.81 ±10.28)% respectively, lower than those of IMRT (P<0.05). Statistically significantly, hematologic toxicity in BMS-IMRT group was less serious compared to that in IMRT group, especially in terms of acute grade 3+ hematologic toxicity. On multivariate logistic linear regression analysis, increased BM-V5, V10 and V20 were significantly associated with the acute grade 2+ hematologic toxicities (p < 0.05 for each association). No statistically significant differences between the two groups were observed in the volume of other OARs irradiated, acute alimentary tract toxicity and urinary toxicity, 3-year local control rate, disease-free survival and overall survival.

Conclusion: Despite of satisfactory dose distribution of target volumes and efficacy, BMS-IMRT is clinically promising in LARC neoadjuvant chemoradiotherapy as a mean of limiting BM irradiation and thus to reduce hematologic toxicity.

Author Disclosure: Y. Wang: None. D. Yu: None. B. Zhang: None.

Yijun Wang, MS

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