Predictors of pathologic complete response after preoperative concurrent chemoradiotherapy of rectal cancer: a single center experience.
OBJECTIVE
To identify possible predictors of pathologic complete response (pCR) of rectal cancer after preoperative concurrent chemoradiotherapy (CCRT).


METHODS
We conducted a retrospective review of 53 patients with rectal cancer who underwent preoperative CCRT followed by radical surgery at a single center between January 2007 and December 2012. The median radiotherapy dose to the pelvis was 54.0 Gy (range, 45.0 to 63.0 Gy). Five-fluorouracil-based chemotherapy was administered via continuous infusion with leucovorin.


RESULTS
The pCR rate was 20.8%. The downstaging rate was 66%. In univariate analyses, poor and undifferentiated tumors (p = 0.020) and an interval of ≥7 weeks from finishing CCRT to surgery (p = 0.040) were significantly associated with pCR, while female gender (p = 0.070), initial carcinoembryonic antigen concentration of <5.0 ng/dL (p = 0.100), and clinical stage T2 (p = 0.100) were marginally significant factors. In multivariate analysis, an interval of ≥7 weeks from finishing CCRT to surgery (odds ratio, 0.139; 95% confidence interval, 0.022 to 0.877; p = 0.036) was significantly associated with pCR, while stage T2 (odds ratio, 5.363; 95% confidence interval, 0.963 to 29.877; p = 0.055) was a marginally significant risk factor.


CONCLUSIONS
We suggest that the interval from finishing CCRT to surgery is a predictor of pCR after preoperative CCRT in patients with rectal cancer. Stage T2 cancer may also be an important predictive factor. We hope to perform a robust study by collecting data during treatment to obtain more advanced results.
Proton Therapy Center, National Cancer Center, Goyang, Korea.
Euncheol
E
Choi
Department of Radiation Oncology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
Jin Hee
JH
Kim
Department of Radiation Oncology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
Ok Bae
OB
Kim
Department of Radiation Oncology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
Mi Young
MY
Kim
Department of Radiation Oncology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
Young Ki
YK
Oh
Department of Colorectal Surgery, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
Sung Gyu
SG
Baek
Chemoradiotherapy; Interval; Rectal neoplasms; Rectum; Stage