New Genetic Advances in Breast Cancer Diagnosis

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.