PHILADELPHIA—A derivative of vitamin A found naturally in sweet potatoes and carrots may benefit consumers with pre-cancerous cells potentially leading to breast cancer, according to new research published by the International Journal of Oncology.

These findings build on previous research showing those who consume plenty of fruits and vegetables can lower their risk of death from breast cancer, encouraging patients with early-stage breast cancer to incorporate healthier foods into their diets.

Researchers in the new study found the vitamin A derivative, retinoic acid, helps turn pre-cancer cells back to healthy breast cells, which could help explain why some clinical studies have been unable to see a benefit of vitamin A on cancer. Sandra Fernandez, Ph.D., assistant research professor of medical oncology, and her colleagues at Thomas Jefferson University, found the vitamin does not appear to change the course of full-blown cancer, only pre-cancerous cells, and only works at a very narrow dose.

Because cells undergo many changes before they become fully aggressive and metastatic, researchers used a model of breast cancer progression composed of four types of cells, each one representing a different stage of breast cancer: normal, pre-cancerous, cancerous and a fully aggressive model.

When the researchers exposed the four breast cell types to different concentrations of retinoic acid, they noticed a strong change in the pre-cancerous cells. Not only did the pre-cancerous cells begin to look more like normal cells regarding their shape, they also changed their genetic signature back to normal. Fernandez's pre-cancerous cells had 443 genes that were either up or down-regulated on their way to becoming cancerous. All of these genes returned to normal levels after treatment with retinoic acid.

"We were able to see this effect of retinoic acid because we were looking at four distinct stages of breast cancer," Fernandez said. "It will be interesting to see if these results can be applied to patients."

Cells that were considered fully cancerous did not respond at all to retinoic acid, suggesting that there may be a small window of opportunity for retinoic acid to help prevent cancer progression. In addition, the researchers showed that only one concentration of retinoic acid produced the anti-cancer effects. Lower concentrations gave no change, and higher concentrations produced a smaller effect.

The next step will be to try to learn whether the amount of retinoic acid required can be maintained in an animal model, and if that concentration will have the same effects as Fernandez observed in cells. If those studies show the same effect, the following step would be to test whether these observations hold true in humans.