One of the most frightening facts of breast cancer is that two people may have the same diagnosis at the same stage, get the same treatment and then have remarkably different outcomes. One consequence of this is that while there is a lot of talk about cures for breast cancer, many women regard the diagnosis as a conditional death sentence.
An article published today online in Nature looks as though it will give us the tools to understand why outcomes vary and what different treatments can help those headed toward a worse outcome. The findings seem also to be well explained in the New York Times.
Two other types of breast cancer, accounting for most cases of the disease, arise from the luminal cells that line milk ducts. These cancers have proteins on their surfaces that grab estrogen, fueling their growth. Just about everyone with estrogen-fueled cancer gets the same treatment. Some do well. Others do not.
The genetic analysis divided luminal cancers into two distinct subtypes. The luminal A subtype had good prognoses while luminal B did not, suggesting that perhaps patients with luminal A tumors might do well with just hormonal therapy to block estrogen from spurring their cancers while luminal B patients might do better with chemotherapy in addition to hormonal therapy.
In some cases, genetic aberrations were so strongly associated with one or the other luminal subtype that they appeared to be the actual cause of the cancer, said Dr. Charles Perou of the University of North Carolina, who is the lead author of the study. And he called that “a stunning finding.”
“We are really getting at the roots of these cancers,” he said.
It looks as though there are going to have to be clinical trials, but there are a number of breast cancer types with discouraging statistics, and now we can hope those can be much more effectively treated soon. As far as I can see, these include ones for which some women have prophylactic mastectomies, since if you carry the gene for them having your breasts removed may be the best option.