Vitamins A and D and Their Combinations for Breast and Colorectal Cancers: Analysis of the Clinical, Epidemiological, Preclinical and Transcriptomic Data.

Background and Objectives: Vitamins A and D have been reported to improve cancer outcomes. In this work, we reviewed recent meta-analyses, preclinical, and transcriptomics data for these vitamins and combinations for breast and colon cancers. Methods: Searches for meta-analyses, preclinical, and transcriptomic data for vitamins A and D in breast and colorectal cancers were conducted using electronic databases from June 2012 to May 2025. Studies describing the effects of vitamin A and D levels (through diet, supplementation, and serum concentrations) on the risk, prognosis, metastasis, and survival rates of breast and colon cancer patients, and the doses needed to achieve these endpoints, were included. Preclinical and transcriptomics studies investigating combinations of vitamins A and D were also reviewed. Results: The reviewed studies showed an inverse correlation between vitamin A intake and the risk and survival rates of breast cancers. Sufficient vitamin D3 levels were associated with improved survival outcomes, lower tumor grades, and less ER- or triple-negative breast cancers. For colorectal cancers, meta-analyses showed conflicting results for vitamin A, but clear evidence that vitamin D reduced both risk and mortality. Preclinical and transcriptomics studies provide compelling evidence that vitamins A and D combinations may be more effective for the prevention and treatment of breast and colon cancers, due to their significant synergistic effects and the larger number of cancer-signaling pathways impacted. Conclusions: Vitamins A and D reduce breast and colorectal cancer incidence, risk and mortality through multiple mechanisms of action, and offer significant potential as therapeutic and chemopreventative agents.