Research Article: Apolipoprotein E Polymorphism and Colorectal Neoplasm: Results from a Meta-Analysis

Date Published: July 16, 2014

Publisher: Public Library of Science

Author(s): Yun Tian, Jirong Wang, Ying Ye, Liqun Sun, Yingrui Fan, Li Wang, Juan Li, Zhaoxia Wang, Keming Wang, Georgina L. Hold.


To investigate the relationship of Apolipoprotein E (APOE) gene polymorphism to colorectal neoplasia (CRN), we performed a systematic review and meta-analysis. Eligible studies were identified through a systematic literature review from PubMed, EMBASE, and the Science Citation Index up to February 2014. A combined analysis was performed, followed by a subgroup analyses stratified by the study design. We used data collected from 8 prospective studies involving respectively a total of 9243 participants and 4310 CRN cases which including 438 patients with colorectal adenoma (CRA), and 3873 patients with colorectal carcinoma (CRC). The pooled data from this meta-analysis indicated there was no significant association between APOE polymorphism and CRN (ε2: P = 0.51, OR 1.04 95% CI 0.93 to 1.16; ε4: P = 0.72, OR 0.98 95% CI 0.90 to 1.07). Interestingly, subgroup analysis demonstrated there was a significant decreased risk for proximal CRN in patients with APOE ε4 (P = 0.0007, OR 0.52 95% CI 0.35 to 0.76). Data showed no significant association between APOE genotype and overall CRN. However, compared with those carry APOE ε3 alleles, persons with APOE ε4 genotype have significant decreased risk suffering from proximal CRN but not from distal CRN.

Partial Text

Colorectal neoplasm (CRN) is an epithelial polyps which resulted from abnormal proliferation of colonic epithelial cells. Colorectal adenoma (CRA) is recognized as the well-established precursors of colorectal cancer (CRC) [1], [2], [3]. Generally, CRA can develop into CRC through an adenoma to carcinoma sequence [4]. CRC is the third most common cancer in world-wide, accounting for 8% of all cancers [5]. For the past decades, the mortality rate of CRC has been declined because of screening colonoscopy. Despite the success of screening colonoscopy for CRC prevention, people will be benefitted by identifying additional risk factors for CRC that might facilitate novel prevention strategies.

Eight eligible studies at last included in this meta-analysis, and 5 studies of them suggested APOE ε4 is a protective factor. In this meta-analysis, we used a total of 9243 subjects and 4310 CRN cases which including 438 patients with CRA, and 3873 patients with CRC from 8 publications to evaluate the association of APOE gene polymorphism with CRN. This meta-analysis suggested that having an APOE allele doesn’t increase the risk of CRN. Although APOE ε4 has been considered to be a protective factor in CRN [25], [34], our results indicated there was no association between a ε4 allele and CRA development.