Safflower oil is not recommended for breast cancer
Safflower (Carthamus tinctorius L.) oil is a polyunsaturated edible seed oil consisting primarily (76%-82%) of the monounsaturated omega-6 fatty acid, linoleic acid. Safflower oil has been shown to have pro-inflammatory properties. Linoleic acid has been shown to enhance the invasion and peritoneal metastasis of gastric carcinoma cells.
Breast cancer-related effects of consuming safflower oil
Safflower oil has the highest proportion of linoleic acid of all common cooking oils. In addition to in vitro studies, numerous experiments using either carcinogen-induced tumors or transplanted mammary tumors in mice have demonstrated that linoleic acid promotes mammary tumor development. Generally speaking, this effect has not been verified by human studies. However, one 2008 study found that women with a specific genotype (ALOX5AP −4900 A>G polymorphism) who consumed a significant amount of linoleic acid in their diets had an increased risk of breast cancer. Another study found increased breast cancer risk among women cooking primarily with high linoleic acid vegetable or corn oil compared to women using olive or canola oil.
Women with breast cancer have been found to have higher levels of omega-6 in their breast tissue than similar women without breast cancer. Several studies have found that higher omega-3/omega-6 polyunsaturated fatty acid ratios are associated with reduced risk of breast cancer. Consuming safflower oil would tend to decrease the ratio for most women because of its high omega-6 content.
Additional comments
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.