Invasive breast cancers classified as estrogen receptor negative and progesterone receptor positive (ER-/PR+) are relatively rare, accounting for up to 8% of breast cancers in the U.S. (this subtype is more common in Asia). In ER-/PR+ tumors, the cancer cells express progesterone receptors, but not estrogen receptors. Women with ER-/PR+ breast cancer are more likely to be premenopausal. Women with high breast density have an increased risk of breast cancer, including ER-/PR+ tumors.

While similar to ER-/PR- disease, women with ER-/PR+ tumors have a somewhat better prognosis. Endocrine treatments such as tamoxifen that are effective for hormone receptor positive breast cancer are less successful in treating this type of cancer, although they are used.

Because ER-/PR+ tumors are rare, very few studies have specifically investigated this subtype. We summarize the available studies below. Please see our article on what ER-/PR+ breast cancer patients and survivors should eat for information pertaining to diet and supplements.