Potential associations have been found between low vitamin D levels and the risk of developing several types of cancer. Meta-analyses of observational studies have found reduced risk of cancer incidence related to vitamin D intake and 25(OH)D levels, particularly for colorectal cancer, although the strength of the associations was classified as weak. Vitamin D receptor and SNAI2 are found to be involved in the metastastic process of osteosarcoma. While randomized controlled trials have not confirmed that vitamin D supplements reduce the risk of cancer incidence, the relative risk of cancer deaths was lower by up to 16% in several meta-analyses.