title: Can dosimetric parameters predict acute hematologic toxicity in rectal cancer patients treated with intensity-modulated pelvic radiotherapy?
abstract: BACKGROUND
  To identify dosimetric parameters associated with acute hematologic toxicity (HT) in rectal cancer patients undergoing concurrent chemotherapy and intensity-modulated pelvic radiotherapy.
  
  
  METHODS
  Ninety-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.
  
  
  RESULTS
  Twenty-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).
  
  
  CONCLUSIONS
  Lumbosacral 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.
authors.affiliation: Department of Radiation Oncology, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Shanghai, China. wjf62313172@163.com.|Department of Radiation Oncology, Fudan University Shanghai Cancer Center, 270 Dong An Road, Shanghai, 200032, China. wjf62313172@163.com.
authors.forename: Juefeng
authors.initials: J
authors.lastname: Wan
authors.affiliation: Department of Radiation Oncology, Lihuili Hospital, Ningbo Medical Center, Ningbo, 315041, China. lkt1982@126.com.
authors.forename: Kaitai
authors.initials: K
authors.lastname: Liu
authors.affiliation: Department of Radiation Oncology, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Shanghai, China. likaixuan11111@163.com.|Department of Radiation Oncology, Fudan University Shanghai Cancer Center, 270 Dong An Road, Shanghai, 200032, China. likaixuan11111@163.com.
authors.forename: Kaixuan
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Shanghai, China. guichaoli11@163.com.
authors.forename: Guichao
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, Shanghai, China. zhenzhang6@hotmail.com.|Department of Radiation Oncology, Fudan University Shanghai Cancer Center, 270 Dong An Road, Shanghai, 200032, China. zhenzhang6@hotmail.com.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000009:adverse effects / Q000627:therapeutic use; D001853:Bone Marrow / Q000528:radiation effects; D000069287:Capecitabine / Q000009:adverse effects / Q000627:therapeutic use; D059248:Chemoradiotherapy / Q000009:adverse effects*; D003131:Combined Modality Therapy; D005260:Female; D006402:Hematologic Diseases / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000009:adverse effects*; D058958:Organs at Risk; D010388:Pelvis / Q000528:radiation effects*; D011379:Prognosis; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided / Q000009:adverse effects; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D012004:Rectal Neoplasms / Q000601:surgery / Q000628:therapy*; D012720:Severity of Illness Index; D012737:Sex Factors
chemical_list: D000964:Antimetabolites, Antineoplastic; D000069287:Capecitabine