Testing in the Era of Precision Oncology
Every cancer diagnosis is as individualized and unique as the person receiving it. From family history to societal and economic background to a patient’s genetic make-up and composition, cancer affects each person with cancer differently.
Initiatives like precision medicine are based in data that suggest that a personalized disease should have its own personalized treatment. As a subset of precision medicine, precision oncology assesses a patient’s unique genetic profile to help align targeted therapies to hit the right cancer subtypes.
In an era of rapid genetic and genomic advancements, testing offers new insights into personalized treatment plans and targeted therapies to improve patient response and outcomes. Although the process is still evolving, oncology nurses are direct lines for information, education, and support to their patients with cancer, especially when it comes to translating the need for whole-genome testing. Understanding the value and limitations of precision oncology, along with the different uses and forms of genetic testing, is vital to ensuring patients and providers are on the same page when it comes to finding the best possible treatment options.
Understanding the Use of Testing in Practice
Often used interchangeably, genetic and genomic testing can mean very different things (https://www.cancer.gov/about-cancer/causes-prevention/genetics/genetic-testing-fact-sheet). As a field of study, genetics typically means the study of one specific gene, separate from other genes, to understand its impact on the human body. In comparison, genomics is the study of many different genes to provide a wider understanding of a person’s genetic behavior and variances across many different points. This nuanced differentiation may lead to patient confusion. With popular at-home testing kits and advertisements for germline tests—which identify hereditary mutations that have been present since birth in the reproductive genes at the DNA level—many patients assume that genetic testing looks only for hereditary factors. They may not understand the use of tumor testing—which identifies acquired mutations that have developed over time—and its results on their cancer care.
ONS member Elisabeth King, RN, MSN, FNP-C, AGN-BC, AOCNP®, CBCN®, senior manager of Clinical Cancer Genomics at City of Hope in Duarte, CA, says that providers need to be armed with information about testing to clearly answer patient questions about precision oncology.
“We often have quite a bit of confusion in the oncology space about genetic testing. When someone says, ‘genetic testing,’ they may be referring to germline testing or somatic testing. Both are important for oncology nurses to be familiar with as they ultimately may impact patient care,” King says. “Somatic testing involves testing the cancer itself and allows us to investigate what DNA changes happened in a particular cell to turn it into cancer. This information may have implications for prognosis or treatment planning. Germline testing involves testing benign tissue, such as blood or saliva, in a patient who may or may not have cancer. It’s typically done to determine if a patient has an elevated risk for future cancers.”
For ONS member Deborah H. Allen, PhD, RN, CNS, FNP-BC, AOCNP®, director of nursing research and evidence-based practice at Duke University Health System in Durham, NC, the promise of testing means preventing patients from undergoing unnecessary or ineffective treatments depending on their tumor.
“If we know that a treatment won’t work for a certain tumor’s genetic profile, then there’s no sense in exposing a patient to that therapy,” Allen says. “That means reducing potential harm and, hopefully, improving quality of life. In the past, patients would have received standard of care because we didn’t have tumor profiles built or access to targeted agents. Undergoing multiple treatment options was leading to complications, including secondary cancers for patients. Having a precision oncology approach helps reduce patient exposure, limiting the harm done by unnecessary treatments.”
Forms of genetic testing and cancer care have a long history, dating back nearly 50 years.
“Precision medicine has been in the oncology space for a long time. Oncologists started testing breast cancers for estrogen receptors in the 1970s to evaluate efficacy for endocrine therapy,” King explains. “More recently, oncologists have begun taking advantage of a specific DNA repair defect found in many ovarian cancers and are using PARP inhibitors for women with BRCA
mutations. With more targeted therapies, we can often see improved effectiveness without the side effects and risks associated with cytotoxic chemotherapy.”
Testing for patients with cancer holds promise and possibilities for effective treatments. However, Allen and King both caution the limitations of precision medicine and its targeted therapies.
“Although targeted agents may have more potential to work on a given cancer, it’s definitely not a guarantee,” Allen says. “Oncology nurses are in a prime position to help their patients understand the benefits of testing, along with the limitations of precision treatments in practice. We can’t say to patients, ‘This will definitely work.’ We can only tell them that we believe it has a greater chance to work with their tumor profile.”
Tackling Common Misconceptions
With new and rapidly evolving sciences, myths and misconceptions may spread among patients and practitioners. Oncology nurses must recognize what is fact and what is fiction when it comes to genetic testing and how it informs treatment decisions. By understanding the potential and the limitations of testing results, nurses can equip their patients with the best information possible.
“I see two common misconceptions when talking about genetic testing and precision oncology. When we have the outcome of a test and it reveals a mutation, patients often assume that if we’ve identified it, we have a dedicated agent for it. That’s not always the case,” Allen says. “With the push for big data, the Human Genome Project, and the Precision Medicine Initiative, science has uncovered more mutations than we have treatments for—expanding across all disease types. Another common misconception is when patients believe that because their genetic testing revealed something, then the disease is therefore hereditary. Obviously, that’s simply not always the case and explaining the difference in testing types can eliminate that confusion.”
King says that patients and their family members may misunderstand the extent and reach of precision medicine, and oncology nurses can play a vital role in dispelling those myths and providing patient education.
“Patients often think that precision oncology is an option for all cancer types and all mutations, but unfortunately this is not the case,” King says. “Many cancers do not have specific molecules that we can target, and standard chemotherapy is sometimes their only option.”
Both Allen and King emphasize that staying educated and up to date with emerging precision medicine developments can help oncology nurses address misconceptions from their patients. (See sidebar for a list of educational resources.)
Shedding Light on Genetic Testing and Precision Oncology
Ultimately, nurses forge unique relationships with their patients, acting as liaisons to the care team and translators for complex medical ideas.
“Nurses are great at introducing the topic of testing and how it interplays with treatment planning,” Allen says. “They can explain that it isn’t the be-all, end-all of care, but it’s a promising beginning for patients and providers. Oncology nurses are in a prime position to explain what is known and what isn’t known about a test’s results and how it impacts treatment. And nurses can ensure that patients understand that even if a targeted therapy is available for their mutation, they might not respond to that treatment. They can help shed light on the complexities surrounding genetic testing and personalized care.”
King says that as precision oncology grows and testing for more cancer mutations becomes more widely available, oncology nurses will be at the forefront of personalized medicine and genetic testing breakthroughs.
“There are ongoing debates about whether we should be doing expanded tumor testing for every patient who walks in the door,” King says. “As testing becomes more automated and more therapies become available, I suspect that this will become a real possibility. We know that our knowledge and technology will continue to advance, and I am looking forward to seeing more options like chimeric antigen receptor T-cell therapy or CRISPR in the future. It’s an exciting time to be an oncology nurse.”