Scientists discover why some breast cancers are drug resistant

April 14, 2016

In a new study funded by Breakthrough Breast Cancer and Cancer Research UK, researchers examined cancer cells which contained a faulty version of the gene BRCA2.

Women who inherit this faulty gene are at a much higher risk of developing breast and ovarian cancer.

BRCA2 is involved in repairing damaged DNA but cells containing faults in this gene accumulate even more genetic damage as they grow and multiply.

It is this feature which renders them extremely sensitive to cancer drugs that damage DNA, such as PARP inhibitors and carboplatin; BRCA2 cancers can become resistant to these therapies very quickly and is one of the main reasons why treatment fails.

When the research team examined the condition of the BRCA2 gene in cells that had become resistant, they found that the BRCA2 gene had re-activated itself and this in turn allowed the cancer to repair its damaged DNA and survive.

The researchers believe their discovery could lead to new treatments that make resistant cancer cells sensitive to treatment once more.

Professor Alan Ashworth from Breakthrough Breast Cancer says this genetic mechanism allows cancer cells to survive by changing the way treatments affect them.

Professor Herbie Newell, the executive director of translational research for Cancer Research UK, says drug resistance is a problem common to all types of cancer which is poorly understood and by understanding this process patient treatment can altered to counteract the problem of resistance.

The researchers believe this particular mechanism of resistance might be a common way by which many other types of cancer become resistant to treatment.

The Breakthrough Breast Cancer Research Centre at The Institute of Cancer Research is Europe's leading cancer research centre.

The authors note that some of the patients who were coded as having Medicaid insurance were likely to have been enrolled after diagnosis, and thus their later stage at diagnosis may not reflect ability to obtain cancer screening and timely diagnosis among individuals with Medicaid coverage but instead, barriers to medical care due to lack of health insurance.

The study also found African American patients were significantly more likely to be diagnosed at a more advanced stage diagnosis for many cancers, indicating that beyond the effects of health insurance, other barriers likely exist for Black patients related to early diagnosis and prompt medical care.

"The findings of this major study are critical, not only for the 47 million Americans who have no health insurance, but also for our nation," said John R. Seffrin, Ph.D., chief executive officer for the American Cancer Society. "The fact is, too many cancer patients are being diagnosed too late, when treatment is harder, more expensive, and has less chance of saving lives. We must begin to remove the barriers that stand in the way of early diagnosis and timely access to medical care if we are to give all cancer patients an equal chance in the fight."