Breast Cancer Odds Revealed With New Genome Scores
Back in 2013, the “Angelina effect” was born, after the Oscar-winning actress, Angelina Jolie encouraged women to seek genetic testing to find out their chance of developing breast cancer.
Many listened and went to discover whether they had the “faulty gene” known as BRCA1, writes MIT Technology Review. However, many didn’t find the answers they were looking for. This was largely because only 10% of women with a family history of breast cancer are ever found to have an inherited cancer gene.
But, Myriad Genetics, the same company that Jolie used to test her genes, has now began offering a new type of DNA test that could eventually tell any woman her risk of breast cancer.
Instead of checking notorious genes like BRCA1 and BRCA2, another gene with variations tightly linked to breast cancer, it instead looks for small clues distributed throughout a woman’s genome. It then adds these together, in what is called a “polygenic” risk score. In some particular cases, women are learning that their potential risk of breast cancer is 60% or more.
Peter Kraft, an epidemiologist at Harvard University who is involved in the genetic studies of breast cancer, explained, “It’s like we’ve discovered another BRCA, but it is not one gene.”
Myriad has become the first large company to market such a test. There has even been discussions that in addition to breast cancer, tests to predict who will get Alzheimer’s or suffer a heart attack are in development.
Within the test, Myriad combined 86 DNA variants with a person’s history, including information on how old a woman was at puberty. The results can be as strongly indicative of breast cancer risk as a mutation in the BRCA gene, but those odds will apply to many more women.
For now, the test which began being offered in September, is only available for women of European background who have a family history of cancer.
The company have recognised that further research is needed to build genetic predictors for blacks or Hispanics.
Ora Karp Gordon, a cancer doctor in Los Angeles, believes that the scores are helping patients she calls the “worried well” who don’t have a BRCA mutation but do have a frightening family history of cancer. For approximately, one in five of those women, the extra information is able to determine whether they are really in a high risk category or not. If they are, she is then able to give them the correct support and guidance, which may include having mammograms at a younger age and getting MRI tests.
However, she is concerned that the predictions are’t yet completely certain, an stresses that the scores can’t be taken at face value.
Naturally, such advancements lead on to the bigger question of whether every woman should get the test. “That is where technology is going to push us, but I don’t think we have the infrastructure in medical care [yet] to give everyone a personalised and accurate risk assessment,” commented Sara Pirzadeh-Miller, assistant director for cancer genetics at the University of Texas Southwestern Medical Centre.
Risk scores can be very easily calculated for anyone whose genome has been analysed, therefore it might not be too long of a wait until direct-to-consumer testing companies get involved in predicting serious common diseases.
For example, it is becoming more common for newborns and even IVF embryos to be sequenced. At least one company has expressed plans to use risk scores to predict disease risk even before people are born.