As cancer research continues to bring diagnostic and preventative care to the forefront of health care technology, scientists have determined that genetic tests can yield great insight into the potentially fatal disease. Especially in the cases of women with ovarian or breast cancer, genetic testing can provide treatment-driven results and alert of possible lineage implications. Despite clear links between genetic testing and informed decision-making, the rate of women undergoing these potentially lifesaving tests does not adhere to current guideline suggestions.
The low number of women receiving genetic testing is the focal point in a new research study within the Journal of Clinical Oncology (2019;37(15):1305-1315).Through examining the clinical genetic testing and results of patients with breast and ovarian cancer, the NCI study found that actionable pathogenic variants could, in fact, be detected. However, the rate of testing in ovarian and breast cancer patients is only around 31 percent. National guidelines have recommended that nearly 100 percent of cancer patients undergo genetic testing for many years.
"There had been no prior study of the use and outcomes of genetic testing in an unselected population of breast and ovarian cancer patients that represented the diversity of patients and health care settings in the United States. We thought this was essential to understand the value of genetic testing in patient care, and thus we undertook this work," shared Allison W. Kurian, MD, MSc, lead author of the study and Associate Professor of Medicine and Health Research and Policy at Stanford University School of Medicine.
Study Details
To conclude that actionable pathogenic variants could be detected via genetic testing, Kurian and her colleagues studied 77,085 patients with breast cancer and 6,001 with ovarian cancer. All participants were women 20 years of age or older who resided in either California or Georgia between 2013 and 2014. Furthermore, they had all been diagnosed prior to entering the study.
Using four laboratories to perform germline cancer genetic testing, researchers were able to assess patient results at the gene level in search of prevalent pathogenic variants. This clinical testing more specifically demonstrated that patients with breast and ovarian cancer in two large, diverse states had an 8-15 percent prevalence of actionable pathogenic variants. These are variants that cause a "misspelling" of the gene and are anticipated to result in a faulty protein, increasing risk of disease.
"It is very important to me to advance the quality of care that we can offer to our patients living with cancer and to their family members," Kurian stressed. "This study reflects a strong partnership between the National Cancer Institute, state cancer registries, genetic testing laboratories, and academic investigators. Perhaps the most novel aspect of this work is the data linkage between clinical genetic test results and cancer registry data, which has not been conducted on this scale before."
Understanding the Implications
Genetic testing is known to identify variants that can help lead to the possible prevention of future cancers, and to promote a general understanding the cancer risk imposed on family members. Through genetic assessment, family members who may be at risk can begin addressing their own testing and prevention options sooner rather than later.
"Patients with pathogenic variants in certain genes, such as BRCA1 and BRCA2, are more likely to gain benefit from specific targeted therapies known as the PARP inhibitors. This is just one example," Kurian exemplified. "Generally [breast cancer and ovarian cancer genetic testing] are quite similar, but sometimes the specific genes tested will vary slightly."
Beth N. Peshkin, MS, CGC, Professor of Oncology and the Director of Genetic Counseling at Georgetown University's Lombardi Comprehensive Cancer Center, added that many women today who are strong candidates for genetic testing simply are not being told that they are good candidates for genetic testing-leading them to go untested. Alternatively, she added that, while some patients do fear their results, others are more concerned with the cost or logistics of undergoing these tests.
"The bottom line isn't that women are necessarily reluctant to undergo genetic testing, but rather there are a combination of factors contributing to their decisions to not get tested," Peshkin explained. "One major factor is that women are not being referred appropriately or offered testing the way that they should be. In other cases, they may not understand what the implications are in the distant future or for family members."
Peshkin continued by sharing that many studies have shown that the rates of testing are lower than what is expected by guidelines. The issue with providers not appropriately identifying candidates for counseling and testing has created complex questions requiring complex solutions. Depending on the provider, health system and patient, the guidelines must become increasingly uniform to identify all appropriate candidates.
"I think that implementing technological solutions can help ensure that the appropriate candidates are flagged to providers, that providers understand the mechanisms by which to refer patients to genetic counseling, and when appropriate to provide referral information to telephone genetic services is critical," Peshkin said. "There should be no reason that women who are appropriate candidates for genetic testing cannot avail themselves to these services."
Genetic Testing Priority
Ultimately, the key finding from the journal study is that, while researchers understand the importance of genetic testing in breast and ovarian cancer patients, they cannot be certain why the number of women taking advantage of the resource is so low. Many researchers suspect that this is because genetic testing is not being placed high enough on the priority list when these patients are initially diagnosed and treated.
"Studies like ours provide data to help [patients and providers] understand the scope and magnitude of the problem [surrounding the lack of women undergoing genetic testing,]" Kurian stressed. "Educating clinicians and patients about the importance of genetic testing in [the laboratory] setting is an important next step."
She further noted that today the results of genetic testing have significant impact on how providers take care of patients and their families. Yet, there is still much that these providers and researchers do not know regarding the long-term outcomes of genetic testing and targeted interventions among patients and their relatives.
Therefore, large, population-based studies have become critical to uncovering more answers. Moving forward, much like Kurian and her team, the National Comprehensive Cancer Network, American College of Obstetrics and Gynecology, U.S. Preventive Services Task Force, American Society of Breast Surgeons, and ASCO are all working diligently to place a greater emphasis on the need for genetic testing in breast and ovarian cancer patients overall.
Lindsey Nolen is a contributing writer.