OBJECTIVETo determine the association of CD133 expression with the sensitivity to radiotherapy among rectal cancer patients.

METHODSThe clinical data of 32 rectal cancer patients was retrospectively collected for patients who received a short-term preoperative radiotherapy(5 Gy/d,×5 d) from 2008 to 2010. Pretreatment tumor biopsies were immunostained for CD133 expression. Rectal cancer regression grade (RCRG) was used to evaluate the sensitivity of the rectal cancer to preoperative radiotherapy. The correlation of CD133 expression and sensitivity to radiotherapy was analyzed.

RESULTSCD133 differentially expressed in rectal cancer tissue with 17 high expression and 15 low expression. The expression of CD133 was associated with the differentiation of rectal cancer with higher expression of CD133 among poorly differentiated rectal cancers(P<0.05). Among the CD133-high patients, two patients showed 1st RCRG, five patients showed 2nd RCRG and ten patients showed 3rd RCRG. For the CD133-low patients, there were five 1st RCRG, seven 2nd RCRG and three 3rd RCRG. There was a significant association between CD133 expression and sensitivity to radiotherapy (P=0.037). Multivariate logistic regression analysis showed that the expression level of CD133(P=0.027) and the differentiation of rectal cancer(P=0.046) were independent predictive factors for the sensitivity of rectal cancer to radiotherapy.

CONCLUSIONSCorrelation between CD133 expression and sensitivity to radiotherapy of rectal cancer may exist, which may be helpful in predicting the sensitivity of rectal cancer to preoperative radiotherapy.