Communicating with patients about the decision to undergo tumor testing is much like conversations in other areas of cancer care. Patient motivation, expectations and concerns, as well as a psychological response to the cancer diagnosis and its treatment, will all play a role in decision making about somatic tumor testing. The provider’s counseling skills can support decision making. Some messages about somatic tumor testing you might want to discuss with Carole include:
The goal of testing
The primary goal of tumor testing is to identify possible personalized (targeted) treatments for a patient’s cancer type. Somatic tumor testing is used to find DNA changes, or variants, that exist in cancer cells. Some of these variants may play a role in how cancer grows, spreads, and responds to treatment. Therefore, somatic tumor test results can sometimes help clinicians choose the right medicines to treat a person’s cancer.
The benefits of testing
Tumor testing may identify treatments that may not be apparent based on existing pathology reports. In some situations, tumor testing can also provide information about prognosis.
Patients may ask how likely it is that tumor testing will identify a targeted treatment. This is a new area of medicine with varying rates of utility reported in different studies. Studies have shown that 8-38% of patients will have a change in cancer management based on tumor results, such as receiving a different therapy or enrolling in a new clinical trial. As research advances, more precise estimates of the usefulness of tumor testing will become more readily available.
The limitations and potential harms of testing
There are limitations to the testing itself and in the availability and therapeutic benefit of targeted treatments.
Patients may receive a result that is uncertain or inconclusive, either because a variant of uncertain significance was identified or because there is not a clear recommendation for treatment based on the results. Discussing these limitations with patients will help set realistic expectations.
In general, there are no physical risks of testing (other than those associated with a new biopsy, if indicated). However, there is the risk of patients having unrealistic expectations, resulting in disappointment, anxiety or distress after receiving tumor results. This is because the result may:
- Not be helpful in identifying new treatments
- Identify genetic variants that have uncertain significance for treatment
- Identify genetic variants that do not have an associated treatment
- Show that the patient is eligible for medicine that their insurance does not cover
- Show that the patient is eligible for a clinical trial that the patient cannot participate in, due to eligibility criteria or distant location.
Targeted treatments may improve patient outcomes but are unlikely to cure cancer for most patients. Some patients may not respond at all or may respond favorably for a period of time before the tumor develops resistance and stops responding to the treatment.
Tumor testing could also identify a potential inherited genetic variant. In this case, additional evaluation and testing are often indicated. If an inherited genetic variant is found, the patient’s relatives may be at increased risk for cancer or another disease. While some patients may be distressed to learn this information, others may see this as a benefit of testing.
The logistics of the testing process
Testing can be ordered through a commercial lab and there may be options for obtaining testing through research protocols. Each of these options has advantages and disadvantages--including access to experts, research participation, cost, and time--that should be discussed with the patient to determine the best choice for him or her.
Discuss the sample requirements for testing, including whether sufficient tumor tissue exists or if a repeat biopsy is necessary. If a “liquid biopsy” is considered, rather than analysis of a tumor block, a blood sample is all that is required.
Patients often have questions about the turn-around time for receiving results. It can take several weeks to get results back from tumor testing. The anticipated timeline should be discussed with the patient in terms of the potential benefits of a newly identified targeted treatment versus a potential delay in treatment waiting for results.
Communicating about the goals of genomic tumor testing and the associated benefits and limitations with patients like Carole will guide decisions regarding whether the test is right for them. Each patient’s situation and values are unique, and every patient will weigh these considerations individually. Carole, for example, may have difficulty with uncertainty. Others may be willing to accept uncertainty in hopes of identifying a new therapy or receiving a prognosis. As a clinician who understands these complex issues, your role can be instrumental in guiding patients through the decision-making process.
- Talking to Cancer Patients about Genetic Testing. This video from MedPage today is part of the ASCO Clinical Pearls series.
- Precision Medicine for Your Practice: Exploring Somatic Cancer Panel Testing. Learn how to determine when somatic cancer panel testing is appropriate for your patients and how to interpret results of such testing in this free CME.
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