In the last few years boron (B) compounds became increasingly frequent in the chemotherapy of some forms of cancer with high malignancy and of inoperable cancers. As more B-based therapy chemicals are developed it is necessary to review the correlation between B and the incidence of different forms of cancer, the biochemical and molecular mechanisms influenced by B and to explore the relevance of B in the chemoprevention of cancer. This minireview analyzes dietary and therapeuptic principles based on the chemistry of B compounds. We summarize studies correlating B-rich diets or B-rich environments with regional risks of specific forms of cancers, and studies about the utilization of natural and synthetic B-containing compounds as anticancer agents. We review mechanisms where B-containing compounds interfere with the physiology and reproduction of cancer cells. Types of cancers most frequently impacted by B-containing compounds include prostate, breast, cervical and lung cancer. Mechanisms involving B activity on cancer cells are based on the inhibition of a variety of enzymatic activities, including serine proteases, NAD-dehydrogenases, mRNA splicing and cell division, but also receptor binding mimicry, and the induction of apoptosis. Boron-enriched diets resulted in significant decrease in the risk for prostate and cervical cancer, and decrease in lung cancer in smoking women. Boron-based compounds show promising effects for the chemotheraphy of specific forms of cancer, but due to specific benefits should also be included in cancer chemopreventive strategies.