Apoptosis as a Prognostic Factor in Colorectal Carcinoma: Comparison of TUNEL Method and Immunohistochemical Expression of Caspase-3

The development of colorectal cancer is known to be characterized by a sequence of events during which normal colonic epithelium gradually transforms to carcinoma, the adenoma-carcinoma sequence. Apoptosis plays an important role in the development and maintenance of tissue homeostasis. Currently, there is no agreement in the literature about the prognosis of apoptosis in colorectal cancer. The number of studies examining the expression of caspases in colorectal cancer is very limited, and they have not examined any correlation between expression and patient survival. This study included histologic samples from 179 patients diagnosed with colon cancer. We used the TdT-mediated X-dUTP nick end labeling method and caspase-3 labeling to identify the degree of apoptosis. Our results show that lower apoptotic index measured by TdT-mediated X-dUTP nick end labeling method and lower immnuhistochemical expression of caspase-3 is associated with shorter disease-free survival and overall survival. However, only apoptotic index is proven to be an independent survival indicator. The results of our study are consistent with the proposed models of carcinogenesis of colorectal cancer that emphasize resistance to apoptosis as a decisive factor in the progression of the disease and resistance to treatment.