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Lack of Vitamin A-Related Protein May Increase Breast Cancer Risk (dateline March 20, 2000)

A preliminary study at the Mount Sinai School of Medicine in New York has found that cancerous breast tumors often lack a protein involved in vitamin A metabolism. According to the researchers, women who lack the protein CRBP (cellular retinal binding protein) may be at a greater risk of developing breast cancer because they are unable to use vitamin A from their diets to protect against cancer. Vitamin A is a key factor in cellular formation. Several studies have shown that vitamin A helps protect against cancers in humans and animals.

In the study, researchers analyzed normal breast tissue samples taken from women who had breast reduction surgery along with samples from breast cancer patients (these samples included both the cancerous breast tissue and the surrounding non-cancerous tissue). According to lead researcher Dr. Rafael Mira-y-Lopez, the CRBP protein was lacking in approximately 24% of the breast cancer samples. However, the protein was present in all 15 normal samples from the breast-reduction patients. Though the researchers are unsure of the protein’s function, Dr. Mira-y-Lopez said that the most basic interpretation of the data indicates that breast cancer somehow "turns off" the CRBP protein.

The study suggests that while vitamin A may help protect against breast cancer, women who receive sufficient amounts of vitamin A in their diet may still be at an increased risk for breast cancer if the protein is somehow compromised within the body. Interestingly, Dr. Mira-y-Lopez noted that the CRBP protein was absent in both early stage breast cancers (such as ductal carcinoma in situ ) and late stage cancers, indicating that the loss of the protein may occur early in breast cancer development.

While the research is promising, Dr. Mira-y-Lopez and colleagues insist that the findings are not substantial unless they can be confirmed in larger studies. If future findings are similar, physicians may eventually test for the CRBP protein to determine whether a patient is at a greater risk for breast cancer. If the lack of the protein is truly prohibiting cells from using vitamin A, researchers will also investigate whether giving patients retinoic acid (the active form of vitamin A) can help prevent breast cancer. Dr. Mira-y-Lopez believes his study helps point researchers in a new direction: investigating how breast cells use vitamin A.

With the increased popularity of vitamin and mineral supplements, several other recent studies have investigated the effects of vitamins on breast cancer risk. A study conducted at the Istituto Nazionale Tumori in Milan showed that fenretinide, a non-toxic drug related to Vitamin A, may significantly reduce the chances of recurrent (returning) breast cancer in pre-menopausal women. On the other hand, a study at the University of North Carolina-Chapel Hill showed that vitamin A and vitamin E kept cancer cells from dying in laboratory rats (the study has not yet been confirmed in humans). Breast cancer patients are encouraged to check with their doctors before taking dietary supplements.

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