ROLE OF P53 AND P21 WAF1 DETECTION IN PATIENT SELECTION FOR PREOPERATIVE RADIOTHERAPY IN RECTAL-CANCER PATIENTS/

BACKGROUND: Recent studies showed that p53 and p21 map play major role s in determining tumor radiosensitivity through the apoptosis pathway, The aim of this study was to investigate the predicting value of radi osensitivity in human rectal carcinoma. METHODS: p53 and p21/WAF1 expr essions in formalin fixed, paraffin-embedded, preradiation biopsy samp les from 49 patients with primary rectal carcinoma were analyze immuno histochemically. p53 and p21 expressions and their relationships with histopathologic changes after radiation and other clinical features we re evaluated. RESULTS: Expressions of p53 and p21/WAF1 were 49 and 28. 6 percent, respectively. In 36.7 percent of total tumors, significant histopathologic effect can be observed. There was a significant invers e expression of p53 and p21. Most of the p53(+) or p21(-) tumors were radioresistant, and the majority of p53(-) or p21(+) tumors were radio sensitive. Tumors size in the radiosensitive, p53(-), or p21(+) group decreased more significantly than in radioresistant, p53(+), or p21(-) group (P < 0.01), and patients with radioresistant, p53(+), or p21(-) tumors had more local recurrence. more distant metastasis, and a shor ter five-year survival rate than those with radiosensitive, p53(-), or p21(+) tumors, but without statistic significance. No statistically s ignificant correlation can be observed between other tumor clinical fe atures and radiosensitivity, p53, or p21 expressions. CONCLUSION: Immu nohistochemistry detection of p53 and p21 expressions may be useful pa rameters for more radiosensitive patients selected for preoperative ra diotherapy.