Although not statistically significant, these results support further research into (i) whether supplemental vitamin D<sub>3</sub> , alone or in combination with calcium, may increase DNA mismatch repair relative to proliferation, increase TGFβ<sub>1</sub> expression, and decrease autocrine/paracrine growth promotion relative to growth inhibition in the colorectal epithelium, all hypothesized to reduce risk for colorectal carcinogenesis; and (ii) the expression of MSH2 relative to mib-1, TGFβ<sub>1</sub> alone, and TGFα relative to TGFβ<sub>1</sub> in the normal-appearing rectal mucosa as potential modifiable, pre-neoplastic markers of risk for colorectal neoplasms.
These pilot study results support further investigation of whether 1) vitamin D and calcium promote colorectal epithelial cell differentiation, reduce proliferation, and promote apoptosis in the normal-appearing human colorectal mucosa, 2) vitamin D and calcium act as chemopreventive agents against colorectal neoplasms, and 3) mib-1, p21, and bax are potential "treatable", pre-neoplastic, biomarkers of risk for colorectal neoplasms.