Letter to the editor: a meta-analysis of MMP-2 expression on the survival of patients with colorectal cancer

Abstract

Dear Editor: Colorectal cancer (CRC) is one of the most common malignancies in the world and causes serious damage to human health. Despite diagnostic and therapeutic improvements, the prognosis for CRC patients is generally poor. Prognostic factors for survival are useful in the management of CRC patients and to individualize treatment and improve prognosis, and these factors are useful when choosing the treatment on an individual basis, principally disease stage, and performance status. The biological factors involved in carcinogenesis should also be considered as potential survival prognostic factors. Matrix metalloproteinases (MMPs) are able to degrade extracellular matrix components and promote the formation of metastasis. MMPs have an important role in tumor invasion and angiogenesis. MMP-2 is considered to play a critical role in metastasis, and the synthesis and secretion of MMP-2 can be stimulated by a variety of stimuli, including cytokines, during various pathological processes such as tumor invasion, atherosclerosis, and inflammation. Therefore, MMP-2 should be a promising prognostic marker and enhanced expression of MMP-2 in cancer cells has been noticed to be a significant factor to predict poor survival in CRC. A number of studies investigated the relationship between TS expression and survival in CRC patients; however, the results are inconsistent. The aim of this report was to review published studies that investigated the relationship between MMP-2 expression and CRC survival, and to use standard meta-analysis techniques to derive a more precise estimate of the prognostic significance of MMP-2 expression. A computerized bibliography was extracted from the electronic database PubMed, EMBASE, and CBM database until January 31, 2012. The search strategy included the terms: (“colorectal cancer” or “rectal cancer” or “colon cancer”) and (“MMP-2” or “matrix metalloproteinase-2”). All studies matching the eligibility criteria were retrieved and bibliographies checked for other relevant publications. Review articles and bibliographies of other relevant studies identified were hand-searched to identify additional studies. To be eligible for inclusion in this systematic review, a study must meet the following criteria: (1) patients with CRC, (2) it assesses the relationship between MMP-2 and survival, and has been published as a full paper, (3) it has a follow-up time exceeding 3 years, (4) hazard ratio (HR@@) and its 95 % confidence interval (95 % CI) comparing patients with high MMP-2 expression with patients with low expression were described or statistically extractable from data in the article. When duplicate articles were published, only the newest or most informative single article was selected. Only studies providing information on survival were included; studies investigating response rates only, without survival analysis, were excluded. Care was taken to include only primary data or data that superseded earlier work. Two investigators independently extracted data and reached consensus on the following characteristics of the selected studies. To minimize the bias and to improve the reliability, 2 reviewers checked all potentially relevant studies independently. Potential disagreements were resolved by consensus. The following characteristics were extracted from eligible studies: name of first author, year of publication, sample size, test method, cutoff value, tumor stage, histologic Y. Gao : S. Lin : P. Yuan :M. Wang Department of Pathology, the Fourth Affiliated Hospital of China Medical University, Shenyang 110013, China