April 4, 2011 -- New research on the genetic causes of breast cancer could change the way the disease is diagnosed and treated in the not-too-distant future, according to new research.
The findings, if validated, may help doctors avoid some of the guesswork involved in matching treatments to tumors. That could increase the odds that a therapy will work and decrease its side effects. This is known as personalized medicine, and many believe it will shape how all diseases are treated.
The study findings are being presented at the American Association for Cancer Research (AACR) 102nd Annual Meeting in Orlando, Fla.
“We need to completely redo the way we treat cancer and we have to start with a genomic approach,” says researcher Matthew Ellis, MD, PhD, a professor of medicine at Washington University School of Medicine in St. Louis. “An accurate diagnosis based on the cancer genome can eliminate all this trial and error medicine. There are a whole lot of other opportunities that we are ignoring because we didn’t get the diagnosis right in the first place.”
Genes Hold Key to Breast Cancer Diagnosis
The key to proper diagnosis is in the tumors’ genes. Ellis and colleagues have analyzed and sequenced the whole genomes of tumors from 50 people with breast cancer and compared them to the matched genetic material (DNA) of their healthy cells to get a picture of what was occurring on a cellular and molecular level. Overall, the tumors had more than 1,700 mutations, most of which were unique to the individual. All people in this study had estrogen-receptor positive breast cancer. In these cancers, estrogen feeds tumors, causing them to grow and proliferate.
“There is not a single unifying genetic mutation that causes all breast cancers,” he says. Instead, the new report revealed a group of mutations that play a role in driving the changes that lead to many estrogen-receptor positive breast cancers.
For example, the PIK3CA mutation occurs in 40% of these breast cancers, whereas the TP53 mutation is present in about 20% and MAP3K1 mutations occur in 10% of these hormonally dependent breast cancers, the new study showed.
There are also other much rarer mutations seen in the new study. “If you look at these mutations, you see there are 'drugable' targets and there will be opportunities with currently approved drugs,” he says.
Now Ellis and colleagues plan to validate the findings and move toward trials. “The current paradigm of looking for a one-size-fits-all drug will never work,” he says. Treatment must start with a very precise genetic diagnosis. “Every patient will be diagnosed this way in 10 years, possibly sooner,” he says.
The Future of Breast Cancer Diagnosis
Stephanie Bernik, MD, the chief of surgical oncology at Lenox Hill Hospital in New York City, says that she hopes this type of personalized diagnosis and treatment is not too far off.
“We know it is not just one change that causes cancer, but changes on many different levels,” she says.
“What works for most doesn’t work for all and the new study helps move us closer toward the goal of personalizing breast cancer treatment,” she says.
There is no doubt that this is the wave of the future when it comes to breast cancer diagnosis and treatment, says Marisa Weiss, MD, president and founder of Breastcancer.org and the director of Breast Radiation Oncology. Weiss is also the director of Breast Health Outreach at Lankenau Hospital in Wynnewood, Pa.
“There is no one-size-fits-all treatment plan,” she says. “We need a treatment plan based specifically on the unique nature of the disease.”
Better pairing of treatments to tumors will also reduce the risk of side effects because treatments can spare healthy cells and instead focus only on cancer-causing cells, Weiss says.
“This study is exciting because it gives us a deeper FBI-style report on breast cancer and specifically hormone receptive positive breast cancer,” she says.
“Breast cancer is made up of many different cells and many genetic variants,” she says. “If all cells were identical, we would have cured this disease already.”
The new report “gets us one meaningful, but small step closer to decoding breast cancer,” she says. “We are finding out which genes are the culprits and the next step is to find the therapies that knock them out or get them to retain to normal function.”