Our aim was to examine whether certain molecular markers, specifically p53, p21, p27, and Bcl-2, could be used to predict the tumor response of rectal cancer to neoadjuvant therapy and determine the overall and disease-free survival rates of patients following neoadjuvant therapy. Seventy-seven patients with rectal cancers were used in this study. All of them received neoadjuvant therapy and 53 of them were given radical surgery. Immunohistochemical tests were performed for the four markers mentioned above using biopsy specimens obtained from 70 of the patients prior to radiation. The identical tests were performed for the same markers using excised specimens from the patients after radical surgery. For the pre-radiation specimens, the positive rate for having p27 and Bcl-2 markers was 32.7% and 16.6%, respectively. This rate increased to 73.5% and 41.6% (p=0.001 and 0.012, respectively) in the specimens obtained after the surgery. With respect to "fair response (FR)" of patients, the pre-radiation biopsy specimens showed significant difference for the p53 (-) and p27 (+) markers (p=0.006). Patients with a 3-year overall survival rate were found to have, from their surgical specimens, 92% of the p27 (+) and 75% of p27 (-) markers (p=0.0058). Our study showed: first, the rate of positive identification of molecular markers, p27 and Bcl-2, increased following neoadjuvant therapy. Second, either the p53 (-) or p27 (+) status was a good predictor for FR in the pre-radiation biopsy specimens. Third, patients with p27 (+) markers in the surgical specimens lived longer at 3 years.
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