Colorectal carcinoma: histopathological and clinical characteristics related to KRAS oncogen mutation: our casuistic

Abstract

Colorectal cancer (CRC) is the third most common cancer in men and the second in women, with an estimated worldwide incidence of 1.2 million cases. According to WHO, approximately 608,000 people die annually in the world from this cause. There are multiple genes that participate in its development. Of them the mutation of the KRAS gene is relevant for its therapeutic connotations, since the mutated cases do not respond to anti EGFR therapies.

The objective of this investigation was to identify clinical characteristics and histopathological parameters related to mutational state of KRAS gene in patients with CRC in 115 cases and to determine in 36 cases the cell proliferation index performing immunohistochemistry with Ki 67, comparing it with KRAS mutational state.

The study was descriptive, observational, retrospective and cross-sectional, studying 115 surgical pieces of CRC from our hospital in the period between 7/2013 and 7/2018. The cases were grouped according to the state of KRAS in: wild-type (not mutated) and mutated, analyzing in both age, sex, location, morphology, nuclear grade, mitotic index, necrosis, vascular permeations, perineural infiltrations and pathological staging. 36 cases (18 mutated / 18 Wild type) were selected, in which the proliferation index was analyzed (Ki 67). The data were analyzed with the statistical program InfoStat.

Of the 115 cases, 43% exhibited KRAS mutation and predominated in women (58%), with a mean age of 70 years, located in the right colon with a lower percentage of necrosis. WT (57%) predominated in men (69%), with a mean age of 69 years, in the left colon, with a greater degree of necrosis. No differences were found in morphology, nuclear grade, mitotic index, vascular permeations, tumor infiltrations or tumor staging. The Ki 67 predominated in the Wild Tipe group with 62.8%.

The determination of KRAS gene status is necessary for therapeutic choice. In our study, colorectal neoplasms with abundant tumor necrosis have higher proliferation index (Ki-67) compared to the mutated form. Although other parameters showed no differences, the continuity of the studies could provide more data in the future.