title: Clinical predictive factors of pathologic tumor response after preoperative chemoradiotherapy in rectal cancer.
abstract: OBJECTIVE
  The aim of this study was to identify clinical predictive factors for tumor response after preoperative chemoradiotherapy (CRT) in rectal cancer.
  
  
  METHODS
  The study involved 51 patients who underwent preoperative CRT followed by surgery between January 2005 and February 2012. Radiotherapy was delivered to the whole pelvis at a dose of 45 Gy in 25 fractions, followed by a boost of 5.4 Gy in 3 fractions to the primary tumor with 5 fractions per week. Three different chemotherapy regimens were used (5-fluorouracil and leucovorin, capecitabine, or tegafur/uracil). Tumor responses to preoperative CRT were assessed in terms of tumor downstaging and pathologic complete response (ypCR). Statistical analyses were performed to identify clinical factors associated with pathologic tumor response.
  
  
  RESULTS
  Tumor downstaging was observed in 28 patients (54.9%), whereas ypCR was observed in 6 patients (11.8%). Multivariate analysis found that predictors of downstaging was pretreatment relative lymphocyte count (p = 0.023) and that none of clinical factors was significantly associated with ypCR.
  
  
  CONCLUSIONS
  Pretreatment relative lymphocyte count (%) has a significant impact on the pathologic tumor response (tumor downstaging) after preoperative CRT for locally advanced rectal cancer. Enhancement of lymphocyte-mediated immune reactions may improve the effect of preoperative CRT for rectal cancer.
authors.affiliation: Department of Radiation Oncology, Chungbuk National University College of Medicine, Cheongju, Korea.
authors.forename: Chi Hwan
authors.initials: CH
authors.lastname: Choi
authors.forename: Won Dong
authors.initials: WD
authors.lastname: Kim
authors.forename: Sang Jeon
authors.initials: SJ
authors.lastname: Lee
authors.forename: Woo-Yoon
authors.initials: WY
authors.lastname: Park