Relapse-free survival (RFS) of colorectal cancer patients according to claudin 1, claudin 2, or claudin 4 mRNA expression was not significantly different (after correction for multiple comparisons) when colorectal cancers were examined as a whole or according to CMS groups Although RFS of cancer patients according to claudin 3 expression independently of CMS groups and within CMS1, CMS2, and CMS4 were not significantly different, RFS of CMS4 patients with low claudin 3 expression was significantly worse than that of counterparts with high claudin 3 expression (Figure 7). Here, CLDN2 is linked to cancer.