A meta-analysis of the relationship between lymphatic microvessel density and the survival of patient with colorectal cancer.

Colorectal cancer (CRC) is a frequently observed malignant neoplasm that is a leading cause of cancer death despite recent advances in treatment and research. The role of lymphangiogenesis in CRC development is a source of controversy in current research. We undertook this study to examine the relationship between lymphatic microvessel density (LMVD) and the overall survival (OS) or disease free survival (DFS) of CRC using meta-analysis of recent studies. PubMed and Embase databeases were searched and nine relevant studies including 799 total patients were included. Six studies including 575 patients focused on overall survival (OS) and 3 studies with 224 patients focused on disease free survival (DFS). We performed a meta-analysis to estimate the prognostic role of lymphatic microvessel density by combining separately estimated hazard ratios. A remarkable correlation between LMVD and DFS was observed in pooled analyses using a fixed-effect model (HR 2.29; 95% CI 1.11, 3.48). LMVD and OS showed a pooled HR value of 1.02 (95% CI 0.71,1.33), indicating no significant correlation between LMVD and OS. There was no evidence for significant heterogeneity or publishing bias in both DFS and OS (I2 = 0.0%, P = 0.861; I2 = 48.1%, P = 0.086, respectively). A close relationship was observed between LMVD and DFS, though no correlation between LMVD and OS was apparent. The current meta-analysis suggests that LMVD may be a poor prognostic factor for CRC patients. However, these results should be regarded cautiously and future confirmatory studies are necessary.