Scientists can predict the likelihood of women developing breast cancer by looking for tiny errors in their DNA.

This is achieved by analysing 77 genes that are cancer-risk sites in the DNA. Individually they each have a low impact on cancer risk, but are powerful in combination. With such DNA testing methods developing rapidly, this could eventually transform screening, preventive treatments and even Hormone Replacement Therapy (HRT).

Current methods of DNA tests that are implemented for such purposes are limited, available only to women with the very highest risk of developing breast cancer. They analyse changes such as mutations in the BRCA genes and can give up to a 90% chance of cancer, but are rare.

Cancer Research Calculates Probability of Breast Cancer

The 77-gene method, analyses the genetic code that have a more subtle effect yet have an influence in every woman’s chance of cancer. The team, led by the Institute of Cancer Research in London and the University of Cambridge, were able to calculate the probability of women developing breast cancer. When they analysed the 77 genetic markers of 65,000 European women they found:

  • In women with no family history of breast cancer, the highest-risk group had a 16.6% lifetime risk.
  • In women with no family history of breast cancer, the lowest-risk group had a 5.2% lifetime risk.
  • In women with a family history of breast cancer, the highest-risk group had a 24.4% lifetime risk.
  • In women with a family history of breast cancer, the lowest-risk group had a 8.2% lifetime risk.

Nell Barrie, of Cancer Research UK, outlined the importance and great potential of the study. She said: “This study shows how the genetic map of breast cancer that scientists have been building up over the years might be used to identify women most at risk, so we can take steps to reduce their chances of developing the disease or catch it at the earliest possible stage.”

These new DNA test methods could identify which women need drugs to reduce the risk of breast cancer, it may reduce the need for screening for the lowest-risk women and may spot those at high risk so action can be taken sooner. Having such information could also aide decision making in the choice of whether or not to undergo HRT, as it has many benefits but can also increase the risk of cancer.

Implementation of 77-Gene DNA-Tests

Professor Monserrat Garcia-Closas, of the institute of Cancer research expressed her excitement of the development of new analytical methods. She told the BBC: “I think it’s very exciting at the moment. The discovery of these variant has progressed very quickly in the last five years and I think it’s reaching a plateau. And at that point it’s time to start designing a genetic test that includes all these elements. That’s likely to be reached within a year.”

The greatest challenge could possibly be the incorporation of these DNA tests with current methods. Professor Douglas Easton, of the University of Cambridge said: “We’ve now reached a crucial stage at which all this research can be combined to help target screening and advice to those women who need them the most.”

He added: “There’s still work to be done to determine how tests like this could complement other risk factors, such as age, lifestyle and family history, but it’s a major step in the right direction that will hopefully see genetic risk prediction become part of routine breast screening in years to come.”