“What does the latest news on genetic testing for breast cancer mean for me and my daughter? Two years ago, I had the test for breast cancer — the results were negative. Does this new research mean that my test was not accurate? Is there a chance I could still have a mutation?” I am a breast cancer survivor (diagnosed at age 48), and there’s breast cancer in my dad’s family.”
The simple answer, Tina, is that this new information does not make your test any less accurate. Your test, called full sequence BRCA testing, looked for genetic changes in two tumor suppressor genes (called BRCA1 and BRCA2) that are currently known to be associated with hereditary breast and ovarian cancer.
What this study tells us is that there are other types of genetic changes in these genes (called “genomic rearrangements”) as well as other genes that may help explain why your family has experienced so much cancer. Depending on when you tested, some of these genomic rearrangements may have been included in the testing process.
This study is very exciting news for the field of genetic testing for hereditary breast and ovarian cancer. Since BRCA gene testing began to be offered commercially almost 10 years ago, experts have known that looking at the sequence, or the genetic code, of these genes does not explain the underlying cause of cancer in some families. This is where someone’s family history comes in: the more significant your family history, the more likely your family may carry an unidentified mutation.
Studies like this bring us one step closer to offering more comprehensive testing to families like yours in the future. It is frustrating that the media did not present this research clearly. Articles with titles like “Flaw Seen in Genetic Test for Breast Cancer Risk” caused unnecessary anxiety and confusion for people like you, leading them to question whether their test results were valid, when it really should have conveyed that these new findings are progress!
For others who are interested:
Tina is referring to a study published in the March 22 issue of the Journal of the American Medical Association. The study looked at 300 breast-cancer patients who also had four or more cases of breast or ovarian cancer in their family, and who had negative results with the standard, full sequence BRCA test that is commercially available.
Here are the researchers conclusions: “The mutational spectra of BRCA1 and BRCA2 include many high-penetrance, individually rare genomic rearrangements. Among patients with breast cancer and severe family histories of cancer who test negative for BRCA1 and BRCA2, approximately 12% can be expected to carry a large genomic deletion or duplication in one of these genes, and approximately 5% can be expected to carry a mutation in CHEK2 or TP53. Effective methods for identifying these mutations should be made available to women at high risk.”