OBJECTIVETo analyze the relationship of K-ras mutation with the development of liver metastasis in colorectal cancer patients and the survival outcomes.

METHODSFrom 2003 to 2008, 300 patients who underwent colorectal cancer surgery in the Department of General Surgery of Zhongshan Hospital, Fudan University were assigned to different groups, according to the diagnosis and follow-up results. The mutation of exon 2 of K-ras was detected in primary paraffin-embedded lesions by PCR and Pyrosequencing. The association of gene mutation with the development of liver metastasis and its prognosis was studied.

RESULTSAmong 300 cases, the mutations of exon 2 were present in 120 cases(40%). The G13D mutation was more common in metachronous metastasis group than that in synchronous group(17.0% vs. 8.0%, P=0.041). Multivariable regression analysis showed that G13D mutation was an independent risk factor(HR=1.108, 95%CI:1.032-5.062, P=0.048) for metachronous metastasis. Patients with mutated K-ras had a poorer overall survival compared to those without mutated K-ras for patients without liver metastasis(median overall, 65 vs. 72 months, P=0.039), and for patients who received metastasis resection(median disease-free survival 18 vs. 24 months, P=0.048). Multivariable analysis showed that K-ras mutation was an independent risk factors of overall survival(HR=1.561, 95%CI:1.022-6.422, P=0.045) in patients without liver metastasis.

CONCLUSIONDetection of K-ras mutation may predict the development of liver metastasis and prognosis.