Studies have not established the effect of plums on breast cancer
Plums are a good dietary source of vitamin A and vitamin C and various carotenoids, phenolics and anthocyanins. Chlorogenic acids and glycosides of cyanidin, peonidin, and quercetin are the major phenolics found in plums. Plums also contain fiber and potassium, as well as some magnesium and boron. Plums have been shown to possess antioxidant and anti-inflammatory properties. Chlorogenic acid has been shown to decrease anxiety in mice. Laboratory rats that drank plum juice had improved working memory in a water maze in one experiment. Dried plum (prune) consumption has been shown to improve bone health by improving bone density and strength. Prunes also have a laxative effect. Plums have substantial bile acid binding potential, which has been associated with lower cholesterol and lower risk of heart disease and cancer.
Cancer-related effects of eating plums
Plum extract has been shown to decrease the proliferation of breast cancer cells. Plum extract also has been shown to induce apoptosis and reduce viability of human liver cancer cells. Plum consumption has been found to be associated with reduced risk of head and neck cancer.
Additional comments
Non-organic plums must be washed thoroughly to remove pesticide residue. Anthocyanin and phenolic content and antioxidant activity is higher in plums with dark skin and flesh than in lighter colored plums, and is also higher in the peels than in the flesh of plums.
Note that while we are continually searching for new evidence specifically concerning this food, there is not much interest in it among breast cancer researchers, so few studies are available.