What You Need to Know About the Groundbreaking New Breast Cancer Study

Researchers behind an unprecedented study that is expected to change the way we understand and treat breast cancer, which kills more than 35,000 U.S. women a year, are calling their findings "the breast-cancer equivalent of putting a man or woman on the moon." Here's how the study could affect you and your loved ones.

The findings, published online yesterday in Nature, is part of a federally funded project called the Cancer Genome Atlas, which hopes to be the cancer equivalent of the Human Genome Project — their scientists have already published the genomes of brain, ovarian, colorectal and lung cancers.

This study is the first comprehensive genetic analysis of breast cancer — researchers analyzed tissue from 348 breast cancers — and it's about time, too: they found that most tumors are caused by mutations in 30 to 50 genes and identified four distinct types of breast cancer, each with its own genetic traits: basal-like cancers, luminal A and B cancers, and HER2-enriched cancers. Simply put, "just because it's a breast cancer doesn't mean it's like every other breast cancer," as Brad Ozenberger, head of the Cancer Genome Atlas told USA Today.

So why is everyone so excited that there are so many different types of cancer? Because now researchers are starting to see the links between different kinds of tumors, which means doctors will most likely be able to more effectively treat patients in the relatively near future instead of lumping (gah, horrible unintentional pun) all breast cancers together and therefore administering risky treatments that are too often more trouble than they're worth.

For example, consider triple negative and basal-like cancers, the latter of which is most common in young and African-American women. Currently, most people with these cancers are treated with drugs called anthracyclines that are bad for the heart and can cause leukemia. But researchers found that some forms of these cancers actually resembled forms of ovarian and lung cancer more than other breast cancers, meaning that patients might be able to benefit from drugs already approved for ovarian cancer. "It's incredible," Dr. James Ingle of the Mayo Clinic, one of the study's 348 authors, told the New York Times regarding the triple negative tumor—ovarian cancer connection. "It raises the possibility that there may be a common cause."

Another example concerns HER2-enriched cancers. Breast cancers that have extra copies of the gene HER2 can grow more quickly, so all breast cancer patients with tumors that make too much of it are given Herceptin, which blocks the gene. But the new study found that only cancers that specifically fall within the HER2-enriched category respond readily to Herceptin. Since the drug is expensive and often heart-damaging, knowing exactly which patients need it to beat their disease is crucial. Yet another "stunning finding," according to Dr. Charles Perou of the University of North Carolina, the lead author of the study, is the discovery that, in some cases, genetic aberrations actually cause breast cancer. "We are really getting at the roots of these cancers," he said.

Of course, it'll take a while before we can actually implement these findings — one researcher called the study a "road map" while another said it was a "'stay tuned' story," not a quick fix solution. Doctors won't start swapping out traditional breast cancer treatments with ovarian cancer drugs for quite some time, if at all — researchers have to run clinical trials first, which will take years. But one breast cancer survivor USA Today spoke with "choked up" when she heard that future patients might be able to go without toxic chemotherapy. Another survivor interviewed by the New York Times said she didn't mind the wait. "In 10 years it will be different," she said. "I know I will be here in 10 years."


Genome project links breast and ovarian cancers
[USA Today]

Study Divides Breast Cancer Into Four Distinct Types
[NYT]