A New York Times report discussed how genetic testing could provide “grim data” without guidance for patients. While this is a valid concern, this report does not sufficiently emphasize certain important issues regarding genetic testing, particularly the need for genetic counseling by a health care provider with expertise in genetics before and after genetic testing. (4/5/16)
STORY AT A GLANCE
A patient’s story about how genetic testing offered more confusion than answers was the topic of the New York Times (NYT) report, “When Gene Tests for Breast Cancer Reveal Grim Data but No Guidance.” This report discusses two types of genetic testing: germline testing that looks for mutations in genes that increase cancer risk, and direct sequencing of tumor DNA to look for mutations in the tumor, which might help to optimize treatment.
The report begins with the story of a patient who had germline genetic testing, and was found to have a variation of unknown significance (VUS) in an unspecified gene, which led to confusion about the most appropriate treatment for her. The report then discusses how sequencing DNA from breast cancer tumors usually provides few answers for patients.
While these are valid concerns, this report raises many unaddressed issues. Nor were the ambiguous/troublesome cases in the report counterbalanced by stories of people who benefited from either germline or tumor genetic testing.
The Report Raised Concerns about Genetic Testing:
According to the report, the patient was about to begin radiation therapy after a lumpectomy for breast cancer. Her physician, a radiation oncologist, told her that, “A genetic test showed she had inherited an alteration in a gene needed to repair DNA. Radiation breaks DNA, so the treatment might actually spur the growth of her cancer.” The report also stated that the “surgeon urged her to not take the risk, and to have a double mastectomy instead.”
- There is little research on how people with mutations in BRCA or other genes involved in repairing DNA respond to radiation treatment, nor are there national guidelines that recommend for or against radiation treatment in mutation carriers. A review of limited research published in 2015 says, “The present review also reassures that both BRCA1/2 mutation carriers are not proportionally more susceptible than non-carriers to radiation carcinogenic effects and radiotherapy of the first invasive breast cancer does not increase the risk of subsequent contralateral breast cancer.” Finally, while mutations in a few genes may inform a patient’s radiation therapy, it is critical to recognize that a variant of uncertain significance is not a worrisome finding. It is common, expected and should not change therapy. Patients who get a VUS on genetic testing should consult with a genetic counselor, medical geneticist, or other genetic specialist, since this is an area of great confusion to both non-genetics providers and patients.
“But patients need to be prepared for ambiguities [regarding genetic testing results]. “Typically they are not,” said an oncologist.
- This example underscores the need for genetic counseling by a genetic counselor or medical geneticist before genetic testing. Patients who receive pre-test genetic counseling are made aware that while health care providers can interpret more genetic information than ever before, patients may still have ambiguous results that do not provide clear guidance for treatment or cancer risk management. A genetics expert will discuss the possibility of an ambiguous result to help prepare the patient for that possibility, and then ask if the patient still wants to proceed with testing. Patients are not prepared for ambiguities when they do not see an appropriate health care provider, or when they see a health care provider who doesn’t thoroughly discuss the types of results patients may have, before they consent to genetic testing.
After the discussion with her radiation oncologist, the patient consulted with a medical geneticist, who told her that the mutation she had was not known to be harmful and recommended that she go ahead with the radiation therapy.
- Again, this case underscores how critical it is to have genetic counseling by a genetic counselor or medical geneticist. In addition to genetic counseling before genetic testing, patients should also see a genetic counselor or medical geneticist once the test results become known. This allows for a thorough discussion of what the results mean, how they fit with the patient’s personal and/or family history of cancer, and how they may affect the patient’s treatment and/or cancer risk management decisions. This case also emphasizes the need for better genetics education for frontline physicians who offer genetic testing to their patients.
The report notes that the patient carried a variation of unknown significance (VUS) in an unspecified gene. The report stated that, “Having a variation of unknown significance means it does not destroy the gene’s function, but may alter it—leaving the implications entirely uncertain.”
- This is an inaccurate explanation of what it means to have a variation of unknown significance in a gene associated with increased cancer risk. When a test result shows a VUS, it means that not enough information is available at the time to predict whether the change in the DNA sequence increases the patient’s cancer risk, or if it is not associated with the disease. The VUS may destroy the gene’s function, it may impair it slightly, or it may be harmless. Overall, most VUSs are entirely meaningless and do not impact healthcare. They should generally be ignored; nor should decisions about medical care be based upon a VUS. When a laboratory designates a test result as a VUS, it is acknowledging that a gene change is present, but more research is needed to determine if it is related to cancer development. Because of the inherent uncertainty surrounding VUSs, in this context, expert advice from a genetic counselor and/or medical geneticist is of exceptional importance.
Genetic testing does not offer clear-cut answers for everyone.
- Interpretation of a VUS is difficult for health care providers and patients, but with more people getting genetic testing, and increasingt research on the function of specific types of VUS, researchers will be better able to determine whether or not those variations cause disease. A number of ongoing international efforts are underway to establish extensive databases that will ultimately make more sense of VUSs.
“Yet now, as powerful new precision medicine drugs elicit striking responses in patients with other cancers—lung, colon, melanoma, blood, gastric—metastatic breast cancer patients have been left out.”
- This statement implies that there are no precision drugs for metastatic breast cancer patients. While none were approved at the time of the article, clinical trials have been ongoing for PARP inhibitors, a type of targeted therapy for men and women with both metastatic breast cancer and an inherited BRCA mutation. In addition, open clinical trials are looking at genetic changes in tumors from people with metastatic breast cancer. Such trials are the first step in bringing FDA-approved precision drugs to people with metastatic breast cancer.
This report switches between germline testing and breast cancer tumor gene testing without fully explaining the difference between the two
- Tumor testing looks for mutations that are only present in the tumor. Most of these mutations are not present in other cells because they develop as the cancer grows. This type of testing is different from the germline testing discussed at the beginning of the report.
- The NYT report concludes with a discussion about an oncologist who suggested that his patient have her tumor sequenced. The results, however, showed that none of the mutations found could be targeted with any drug. The physician is quoted as saying, “The results added nothing to her care.” While this particular patient may not have benefited from tumor sequencing, she had the potential to benefit from the process. Other oncologists have suggested tumor sequencing for their patients, and some of those patients have benefitted with targeted drugs. The NYT report gives a one-sided view of tumor sequencing. And while it is true now that most patients don’t benefit from tumor sequence analysis, this is an exciting area of research that many experts believe will one day be an important part of guiding cancer care for many patients.
- The report’s abrupt transition from germline testing to tumor testing may easily confuse readers who are unfamiliar with different types of testing, and give the impression that genetic testing does not change care decisions. It is important to remember that germline testing looks for mutations that are present at birth in every cell in the body, and can be passed on from mothers and fathers to sons and daughters. It is the type of genetic testing that shows whether or not a person is at increased risk for developing cancer, or that a patient’s cancer was likely due to an inherited mutation. People who carry mutations in genes that increase cancer risk are offered options to manage that risk, including increased screening and screening for other cancers associated with that gene mutation. Knowing that a person has an inherited mutation in BRCA or another gene that increases cancer risk can affect treatment decisions, including type of surgery and chemotherapy, as well as opening up the possibility of participating in clinical trials that target cancers with BRCA mutations.
Summary: “When Gene Tests for Breast Cancer Reveal Grim Data but No Guidance”
Despite the shortcomings of this report, it does raise a valid concern: genetic testing can give patients and their health care providers access to lots of information about their inherited gene mutations and the genetic changes that occurred in their tumors. Not all of that information is associated with guidelines for care or treatment, however, and we still have much to learn about how to best interpret and use genetic information. Researchers have access to more genetic data than ever before, and it is a new and exciting time in the world of genetics! But in some cases, we are stepping into uncharted territory, and there will undoubtedly be ambiguities and unknowns. Researchers learn more every day to help healthcare providers provide clearer guidance to patients. Patients need to be told that sometimes genetic testing will give them results that are associated with guidelines for risk management and treatment, but there is a possibility that the test result will not provide clear answers.
Today, when a woman finds that she is a BRCA mutation carrier, she is put on a cancer screening regimen and is educated on all of her preventative care options. Expert guidelines identify how health care providers should care for BRCA mutation carriers—this wasn’t the case when BRCA was discovered in the early 1990s. That doesn’t mean that testing wasn’t worthwhile back then; it was just more confusing than it is today. Today we have care guidelines for Lynch Syndrome patients, PTEN mutation carriers, TP53 mutation carriers and others. Understanding how to care for all of these patients did not happen overnight.
Researchers and healthcare providers will undoubtedly understand more about these variations of unknown significance in the future, and additional treatments will be developed to target more tumor mutations. Today, patients should know that they may have ambiguous test results, and to consider whether or not they want to get genetic testing in the face of this possibility. But, the ambiguity is only one side of this story. Genetic testing regularly provides very important and helpful information to patients. While genetic testing may not always provide clear guidance, it often does, and that should not be downplayed. The bottom line is that it should be pursued in conjunction with experts who are familiar with the nuances of testing so that results can provide maximal benefit to patients.
Tell us what you think of this review by taking our brief survey
(back to top)