To Test or Not to Test? Genetic Testing & Breast Cancer

It may seem like ages ago, but it was within most of our lifetimes’ that scientists studying genetics first mapped the complete human genome as we stepped into the twenty-first century. The power of knowledge has opened doors for medical professionals—and for our community itself—giving us new insights into how, why, and specifically who will be impacted by cancer. It took another ten years, or so, for medical breakthroughs to reach the general public, when the idea of preventative treatment options, famously addressed by notable celebrities, started making waves. And, like most sciences, the next breakthroughs started happening faster. We follow the news on this subject closely, and we want to offer a safe space to discuss the pros and cons of genetic testing options.  

Blood, Sweat, and...Saliva? 

According to Time magazine, getting your family genealogy (with a handy mail-in kit) has become the second-most popular hobby in the U.S., next to gardening.1 It took less than thirty years for the science of genetics to become a commodity in American culture. In actuality, the fact that genetic screening has become less expensive, extremely wide-spread, and well-funded has led to an explosion of new advances. And we’re getting a lot more collaborative. In early February 2020, a study from the Pan-Cancer Analysis of Whole Genomes Project (PCAWG) was able to combine the genetic research of over 2600 genomes from different cancers.2 Prior to this type of study, genetic scientists were studying the tip of the iceberg. Marcin Cieslik, a cancer geneticist co-authoring a paper on the study states, “Whether whole-genome sequencing is ultimately the best method … remains to be seen.” Still, the sheer wealth of new data is uncovering new ground for doctors forming treatment options.

Personal Knowledge, Personal Empowerment

Ultimately, the hope for our community is that this new knowledge may lead to advances in treatment. Knowing what we’re up against should feel empowering. We get all of our combined genetic material from both our mother and father, but women and men who inherit a mutation on these genes have a much higher risk of developing certain kinds of cancer. Understanding whether or not we carry a specific mutation for a disease could lead to more targeted treatment options for certain diseases like breast and ovarian cancer.3 Testing for specific genetic markers may also improve research for others. A new study is linking young adults with early-onset cancer with the genetic markers associated with breast cancer. Patients aged 18 to 39 diagnosed with cancers, typically seen in older patients, are identified as having early-onset cancer, according to medical professionals.4 

The Chaos of Knowing Too Much

Genetic testing for breast cancer rocked the public with the discovery of the BRCA1 and BRCA2 genes. But advances in testing, combined with lower costs to patients and doctors alike, have made things more complicated. For one thing, checking for one or two genetic anomalies, like the breast cancer genes, may no longer be so simple. Multigene panels that analyze dozens of sequences are now much more common, and more convenient than checking for one or two outliers. Patients may discover they carry a mutation for pancreatic cancer or melanoma (CDKN2A), while already being high-risk for breast cancer due to family history. Worse, still, patients could discover they carry a gene for a disease that has no treatment. One oncologist, Kenneth Offit, a cancer geneticist and medical oncologist at Memorial Sloan Kettering Cancer Center, reports seeing several patients presenting genetic mutations like TP53, the gene associated with Li-Fraumeni syndrome, which is untreatable.5 He warns that many patients may not be prepared to uncover potential bombshells from their screening. Learning we may develop an untreatable disease later in life is a heavy burden to carry on top of the fear of developing breast cancer. 

The New Ethics

Knowledge overload aside, the power of genetic testing is changing the way we think about the many diseases that make up cancer—and how to fight back. Like many sciences, the rate at which we gain new insights will likely be exponential. Deciding what to do with this information may be difficult. As genetic testing evolves into multipanel testing and beyond (some specialists are now offering full exome sequencing), the pros and cons of getting screened become more personal. Not every genetic anomaly is crystal clear, and, according to Susan Domchek, a medical oncologist at the University of Pennsylvania’s Abramson Cancer Center in Philadelphia, when an unknown variant is discovered in a genome sequence, it is referred to as a “variant of unknown significance (VUS).”6 These VUSs must be interpreted by the medical professionals at hand. “How you determine whether it’s important or no big deal isn’t trivial,” she explains. Other ethical implications are arising in the treatment of pediatric patients. A full exome panel may help to treat a young cancer patient with an illness they experience today while uncovering a genetic marker for adult-onset cancer later in life. Some doctors question whether they’re doing a test that wasn’t asked for.  

It’s important to note that having a gene for a disease does not guarantee that you will or will not develop the illness. Lifestyle, environment, and just plain luck all factor in whether or not a disease may advance. We must all determine what to do with the information available to us, and no one can make that decision for us. Understanding illness is an emotional journey, and there is no set, clear path or directions. We remain steadfast in our hope that as science learns more about the markers that precede cancer, we will be armed and ready to prevent it. 

“Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.” – Marie Curie