Optimal timing for the administration of capecitabine with preoperative chemoradiation for locally advanced rectal cancer.
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.
Noh
Young Ju
YJ
Department of Radiation Oncology, Ulsan University Hospital, Seoul, Korea.
Choi
Won Sik
WS
Kim
Jong Hoon
JH
Kim
Jin Cheon
JC
Yu
Chang Sik
CS
Kim
Hee Cheol
HC
Kim
Tae Won
TW
Chang
Heung Moon
HM
Ryu
Min Hee
MH
Ahn
Seung Do
SD
Lee
Sang-wook
SW
Shin
Seong Soo
SS
Lee
Jung Eun
JE
Choi
Eun Kyung
EK