[A study of the relationship between the mutation of PIK3CA, PTEN and the occurrence of liver metastasis of colorectal cancer: survival analysis]

Abstract

Objective: To investigate PIK3CA, PTEN status in the primary lesion of colorectal cancer (CRC): relationship with occurrences of liver metastasis and its prognosis.

Methods: Patients with CRC who had the primary tumor resected between 2003 and 2008 were selected and enrolled into three groups according to the occurrence of liver metastasis. The mutations of PIK3CA exon 9 and 20, PTEN exon 5, 7, 8 in primary cancer cells in formalin-fixed, paraffin-embedded specimens were detected by Pyrosequencing, then a statistical analysis was deduced to find out the relationship between PIK3CA, PTEN status and occurrences of liver metastasis as well as the prognosis.

Results: Of all the 300 CRC cases, the mutation rates of PIK3CA and PTEN was 18.2% (51/300) and 16.3% (49/300). The multivariate Logistic analysis revealed that exon 5 mutation of PTEN was one of the independent risk factors of occurrence of metachronous liver metastasis in CRC patients (HR = 1.634, 95%CI: 1.796 - 3.355, P = 0.041). Patients with PTEN mutation had a poorer overall survival in group with synchronous liver metastasis (median survival time 62.0 months vs 71.0 months, χ(2) = 12.942, P = 0.048) while CRC patients who had the liver metastasis resected in group of synchronous and metachronous liver metastasis had a poorer disease free survival rates with PIK3CA mutation (median survival time 16.0 months vs 25.0 months, χ(2) = 9.679, P = 0.037).

Conclusions: The exon 5 mutation of PTEN of CRC is potentially correlated with the occurrence of synchronous liver metastasis. CRC patients who had the liver metatasis resected but with PIK3CA mutation could have a poorer prognosis.