THE RELATIONSHIP BETWEEN K-RAS GENE MUTATION, SOME DEGREE OF DIFFERENTIATION AND TUMOR MARKERS IN ADVANCED COLORECTAL CANCER

Abstract

K-ras gene mutation is common in non-hereditary colorectal cancer. Although the role as a predictive biomarker to anti-EGFR therapy is well defined, its role as a prognostic marker is uncertain. We studied the relationship between the incidence of k-ras gene mutation, the degree of differentiation and the status of tumor markers in patients with advanced colorectal cancer resistant to complex cancer treatment. METHOD: Multicenter, retrospective study done in three oncology clinics in Bucharest from 2010 to 2014. The study included 71 stage III and IV colorectal cancer patients, which underwent surgery and adjuvant polychemotherapy. Under treatment they had an unfavourable evolution, the disease evolved worst in the first year of treatment. We analysed the K-ras gene status, the degree of tumor differentiation and the CEA and CA19-9 tumor markers, in all these patients. RESULTS: Of the 71 studied patients, 27 (38%) had the K-ras mutation. From this, 20 (74.1%) had high levels of CEA, and 16 (59.3%) had significant increases of CA19-9. By comparison, the 44 patients (62%) who had the wild gene, had elevated CEA in 28 (63.6%) of the cases and in 23 (52.3%) of the cases the CA19-9 was elevated. The G1 degree of differentiation was present in 28 patients; 11 (39%) were k-ras(+) and 17 (6%) k- ras(–), G2 was present in 36 patients; 14(39%) k- ras(+) and 22 (61%) k- ras(–), and the G3 was present in 7 patients; 2 (29%) k- ras(+) and 5 (71%) k- ras(–). CONCLUSION: K-ras gene mutations in patients with advanced colorectal cancer are not associated with increased prognostic tumor markers values or with the degree of tumor differentiation. The incidence does not differ significantly from that of the patients without the mutation. Keywords: colorectal cancer, genetic mutation, K-ras, tumor markers.