I could learn a lot from my spit if I wanted to. Thanks to advances in DNA sequencing, I could send my spit off for personal genomic testing and find out my predicted risks for hundreds of diseases and conditions. But I haven’t.
After years of studying the genetics of plants, I’m fascinated by the sometimes dramatic effects of seemingly small genetic differences. So why wouldn’t I want to know what my own genes say about my risks? Because in most cases, I think that knowledge would lead only to needless worry.
I’ve readjusted my attitude, though, after attending Taste for the Cure: A Taste of Science, sponsored by UC San Francisco. Earlier this month, about 250 participants, mostly breast cancer survivors and their families, gathered at the Jewish Community Center to hear directly from UCSF scientists. Ten breast cancer researchers were on hand, with expertise ranging from epidemiology to molecular biology to clinical studies. Their perspectives on the usefulness of genetic testing enlightened me.
Before the event, I was vaguely aware of the controversy over the value of mammography. In June, I heard about the Supreme Court ruling that a gene cannot be patented. The case brought renewed focus to the genes BRCA1 and BRCA2, mutations of which significantly increase the risk of breast cancer. I knew of a friend of a friend who, like Angelina Jolie, learned she had one of these mutations and chose a preventive mastectomy to reduce her risk.
But I hadn’t really considered my own risk until the Taste for the Cure panel discussion on risk-based screening. Researchers have identified 40 single-nucleotide polymorphisms, or SNPs, with well-documented contributions to breast cancer risk, Laura van’t Veer, a molecular geneticist, explained during the discussion. SNPs (pronounced “snips”) are single chemical bases in the 3-billion-base human genome that differ among individuals.
Studies on large populations have shown that certain SNPs can genetically predispose people to breast cancer. Clinicians will soon be able to test patients for all 40 SNPs at once. Then, instead of using the “cookie cutter guidelines” of biannual mammograms for all women over 50, doctors can use genetic and environmental factors to tailor a risk-based screening strategy to each patient, said panelist Elad Ziv, a physician who studies the population genetics of cancer.
Although many women fear that forgoing regular mammograms could have dire consequences, this audience was willing to let the science lead the way. In a hand vote, about two-thirds said they would choose a risk-based screening approach—in other words, that instead of following general guidelines, they would be willing to let personalized factors such as genetics inform their choices about when to get a mammogram.
Persuaded by the audience of cancer survivors, I decided to rethink my aversion to genetic testing, at least when it comes to breast cancer risk. I come from an Ashkenazi Jewish family with a history of breast cancer on my father’s side. Mutations in BRCA1 or BRCA2 are about 10 times more common in Ashkenazi Jews than in the general population. I just turned 30, and hope not to have my first mammogram for another 20 years, by which time breast cancer screening and treatment will surely have improved.
So just in case I am at increased risk, I will consider getting tested. Likewise, several survivors at Taste for the Cure expressed concerns about elevated risk for their adult daughters. However, it’s important to note that there are many types of breast cancer, and most do not result from inherited mutations.
The UCSF researchers stressed that they need more data from patients to better predict who is at risk for what type of breast cancer, and to improve screening and treatment recommendations. The five University of California medical centers teamed up in 2009 to launch the Athena Breast Health Network, which is collecting long-term data from 150,000 women. Each participant fills out a standardized electronic questionnaire when she comes in for a mammogram; she can also choose to submit DNA sequence data. The network has only recently collected enough data to begin research projects.
BreastCancerTrials.org also seeks to involve more patients in research. Its program director, Elly Cohen, called herself “a poster child for the benefits of clinical trials.” Her mother had surgery to remove breast cancer, but died four years later when the cancer returned. Cohen is a 15-year survivor; after her surgery, she received chemotherapy and hormone therapy, both developed through clinical trials. The American Association for Cancer Research projects 18 million cancer survivors in the United States by 2020. Women with breast cancer make up 22 percent of survivors, but only a small fraction participate in clinical trials; Cohen hopes to change this.
While researchers benefit from large amounts of data, for individual patients, a wealth of information can feel like too much of a good thing. One survivor told me that she rarely attends events like Taste for the Cure. “The constant gathering of information makes me crazy,” she said. “I’m living my life.” When it comes to personal genomics, I’ve held a similar view. But if I can send off a vial of spit and get back targeted information to guide my medical decisions, sign me up.