K-ras gene is one of oncogenes,which promotes cells growth and differentiation.Ras protein loses the activity of GTP enzyme because of K-ras mutations,and that may cause abnormal growth,differentiation of cells and promote the occurrence of tumor.Patients with colorectal carcinoma that carry mutations in K-ras gene do not benefit from the administration of anti-epidermal growth factor receptor (EGFR) polyclonal antibodies.Different solid tumors of colorectal carcinoma have different K-ras mutation rates.Different genotypes of K-ras gene (wild-type or K-ras mutant type) affect significantly on treatment options and prognosis.The efficacy of mutant type patients with anti-EGFR antibodies is poor,and the therapeutic effects of 5-FU and FOLFOX are still unclear.

Cancer cell exfoliation,invasion and entry into circulation system is the early event with metastasis,which provide the possibility to formation of clinical metastase.Further research about the circulating cancer cells can help us to understand the mechanism of metastasis and offer the scientific proof against anti-metastasis.The detection of circulating tumor cells and clinical significance were reviewed.