The aim of this study was to determine the incidence and prognostic value of p53 immunopositivity in resectable colorectal cancer distal margins.
Study included 198 patients with colorectal adenocarcinoma, who underwent chemoradiation therapy followed by total mesorectal excision, from January 2007 to January 2012. According to the distance between tumor and margin of distal resection margin patients were divided into 2 groups: 1st – Control group 124 (62,6%) patients – the resection was performed by distal margin in the distance of 2 cm. 2nd – Experimental group 74 (37,4%) patients – the resection was performed by distal margin in the distance of less than 2 cm. Each resected specimen assessed for prognostic marker p53, before and after chemoradiation therapy, to determine optimal length of the tumor distal resection margin.
Histopathological assessment showed tumor positive margins in 21 (17%) cases of control group and 35 (47%) cases in experimental group. IHC analysis of control group revealed that expression of p53 was more than 30% in 47 (38%) cases, whereas 74 samples from experimental group encountered p53 positivity in 19 (26%) cases. The overall median survival of patients was 20 months. A significant correlation was observed between p53 tumor staining and survival (p = 0.039); this significance slightly increased after applying of postoperative adjuvant chemoradiation therapy (p = 0.024). The median survival of patients with p53 protein accumulation was 13 months, opposite to 29 months for those patients without p53 protein accumulation.
The median survival of the patients increased more than twice, when less than 30% p53 positivity was present. These results suggest that aberrant p53 expression is associated with the biologically more aggressive adenocarcinoma and in these cases close distal resection margin, shorter than 2 cm leads to a high incidence of recurrence in approximately 50% cases, however positivity of p53 protein in patients with colorectal cancer leads to poor prognosis.
Clinical trial identification
All authors have declared no conflicts of interest.