title: Optimal timing for the administration of capecitabine with preoperative chemoradiation for locally advanced rectal cancer.
abstract: OBJECTIVE
  Capecitabine is an oral fluoropyrimidine carbamate and it is known as an effective radiosensitizer. Capecitabine and its metabolite reach their peak concentration in the plasma at 1 approximately 2 hours after a single oral administration of capecitabine and the levels fall rapidly thereafter. To verify the radiosensitizing effect of capecitabine that is based on such pharmacokinetic characteristics, we performed a retrospective analysis on the optimal timing of capecitabine administration with performing preoperative chemoradiation for locally advanced rectal cancer.
  
  
  METHODS
  Among 171 patients who were treated with preoperative radiotherapy and concurrent capecitabine administration for rectal cancer, 56 patients were administered capecitabine at 1~2 hours before radiotherapy (group A), and at other time in the other 115 patients (group B). Total mesorectal excision was done at 4 to 6 weeks after the completion of chemoradiation. The radiosensitizing effect of capecitabine was evaluated on the basis of the pathological response.
  
  
  RESULTS
  Complete pathological regression of the primary tumor was observed in 12 patients (21.4%) for group A and in 11 patients (9.6%) for group B (p=0.031). Residual disease less than 0.5 cm (a good response) was observed in 19 patients (33.9%) for group A and in 23 patients (20.0%) for group B (p=0.038). On multivariate analysis, the capecitabine ingestion time showed marginal significance.
  
  
  CONCLUSIONS
  When performing preoperative chemoradiation for locally advanced rectal cancer, the radiosensitizing effect of capecitabine was enhanced when it was administered 1 hour before radiotherapy.
authors.affiliation: Department of Radiation Oncology, Ulsan University Hospital, Seoul, Korea.
authors.forename: Young Ju
authors.initials: YJ
authors.lastname: Noh
authors.forename: Won Sik
authors.initials: WS
authors.lastname: Choi
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Jin Cheon
authors.initials: JC
authors.lastname: Kim
authors.forename: Chang Sik
authors.initials: CS
authors.lastname: Yu
authors.forename: Hee Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Tae Won
authors.initials: TW
authors.lastname: Kim
authors.forename: Heung Moon
authors.initials: HM
authors.lastname: Chang
authors.forename: Min Hee
authors.initials: MH
authors.lastname: Ryu
authors.forename: Seung Do
authors.initials: SD
authors.lastname: Ahn
authors.forename: Sang-wook
authors.initials: SW
authors.lastname: Lee
authors.forename: Seong Soo
authors.initials: SS
authors.lastname: Shin
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Choi