Cancer testing tools used by doctors help classify tumors to better guide treatment. At a conventional cancer center, this might include a genetics screen or biomarker test. Private companies offer expanded cancer tests to assess drug sensitivity and advanced genetic characteristics, sometimes referred to as functional profiling, to understand how tumors may respond to a broad spectrum of therapies. A professional group, the Society of Functional Precision Medicine, now supports this growing field.
It takes rigorous and expensive research before a new diagnostic tool is covered by insurance and integrated into the standard of care, so many of these new tests are not available at cancer centers, but can be purchased.
Because these tests are offered by private companies, it can be difficult to discern if the costs are worth it, and whether the results are actionable. Many oncologists are not familiar with the technology because it is new, so they often won’t have answers or be able to alter treatment plans based on the results.
Yet if you have more advanced cancer or have few treatment options, these testing options, used with the right guidance, can offer insights to support you.
In this article, we define the different tests that have gained popularity, and outline the pros and cons of each one.
What you’ll find on this page
Practical considerations for private testing
Tests can help when:
- You’re near the end of the available standard treatments offered by your doctor, or standard treatments aren’t working, and you want to find a new solution
- You have a rare cancer with few standard approaches that work
- Your cancer has unusual mutations in the primary cancer and is known to be less responsive to standard treatments
- You wish to compare different treatments
- You wish to understand which off-label drug and supplement combinations to include with standard oncology drugs
There are limits to these tests:
- Many substances tested also stay in lab cultures longer than they would in your body, or at doses that are higher than a person can consume. Therefore, the results may not accurately reflect reality.
- Liquid biopsy-based tests are generally unavailable for blood cancers and primary brain tumors.
It’s important to consider:
- Very few people reverse cancer using only off-label drugs or supplements, even when tests indicate they might work
- Interpreting the results properly requires experience and knowledge of how cancer works
- Most conventional doctors don’t use these tests, and cancer clinics don’t always offer the treatments tested, so you may not be able to use the test results to inform your treatment
- Insurance will not cover these tests
One major takeaway: if your cancer has evidence for good treatment outcomes from standard of care, these tests may offer little to you. The benefit scale shifts if you have an advanced or rare cancer that has few standard of care treatment options. Even then, to act on the results, you will need to be working with a practitioner who understands the test and is willing to use the results.
Types of private cancer tests
Circulating tumor cells
A circulating tumor cell (CTC) is a cancer cell that is traveling in your bloodstream; you may also see this referred to as a “liquid biopsy.” Testing for these cells can provide genetic information on the tumor to inform treatment plans, they are also used for early detection in some cases. Your provider may use a CTC test that is FDA approved, but there are also private companies that offer these tests. The Signatera test is now covered by Medicare for specific cancers, ask your provider if you qualify.
What is a liquid biopsy vs. regular biopsy?
A liquid biopsy is a blood test that looks for tumor cells circulating in the blood, often referred to as circulating tumor cells (CTCs). This is in contrast to a tumor biopsy where a sample of the primary tumor is removed surgically; a liquid biopsy is more convenient and less invasive.
Sensitivity and resistance tests
One category of tests analyzes different cancer treatments against circulating tumor cells in the blood, or a tumor sample. These tests are designed to assess which treatments are most effective at killing cancer cells to help a provider choose the best treatment. Some methods reflect real-time tumor biology and capture individual variability that standard tools don’t address.
One study assessing the ChemoID test in glioblastoma patients saw a 30% increase in survival among those who used the test to guide treatment choices.1Ranjan T, Sengupta S et al. Cancer stem cell assay-guided chemotherapy improves survival of patients with recurrent glioblastoma in a randomized trial. Cell Reports. Medicine. 2023 May 16;4(5):101025. A stage 3 lung cancer study looked at responses to treatment compared with sensitivity tests. The analysis showed that patients with higher drug sensitivity tended to have longer disease-free survival than patients displaying drug resistance, suggesting the utility of chemosensitivity testing to choose the most effective treatment.2Chen Z, Zhang S et al. Evaluation of the in vitro Chemosensitivity and Correlation with Clinical Outcomes in Lung Cancer using the ATP-TCA. Anticancer Agents in Medicinal Chemistry. 2018;18(1):139-145.
Gene expression
To determine if your cancer might respond to targeted therapies that inhibit resistance pathways, specific testing can help identify the most suitable drugs. Testing typically examines two key aspects: mutations and over expressions.
Gene expression analysis differs from mutational testing, though these are often confused by the patient. Mutations tend to be fixed within the cancer and help define it—like BRCA, KRAS, or ALK. Gene expression, however, changes in response to treatments, cancer stress levels, and the surrounding environment, making it more temporary in nature.
Tests analyzing immune biomarkers of tumors can provide information on the anticipated response from check-point inhibitor treatment. This type of test would be done at the cancer center providing the immunotherapy treatment.3Daud AI, Loo K et al. Tumor immune profiling predicts response to anti-PD-1 therapy in human melanoma. Journal of Clinical Investigation. 2016 Sep 1;126(9):3447-52.
Mutational analysis
Many large hospital systems run their own tests that only look to see if standard-of-care drugs should be provided to treat specific mutations in certain cancers. In private oncology clinics, primarily in the USA, many FDA-approved testing companies are starting to provide mutational analysis beyond the standard of care, looking at mutations that may be actionable in clinical trials.
Each provider is testing a different number of mutations, with most giving suggestions of clinical trials that could be useful. Ask your care team about mutational testing to see what is available, as there may be a test offered already.
In conclusion
It can be overwhelming to navigate choosing tests if you do decide private testing is right for you. There are many companies that offer these tests; some popular ones include NextGen Oncology, RGCC, and Nagourney Cancer Institute. Before pursuing tests not covered by insurance, discuss with your care team to see if they will be able to integrate the results into your care plan.
Our partner, Patient Led Oncology, goes in-depth into specific tests and offers 1:1 sessions to talk about private cancer choices. You can read about private cancer testing in detail in the Patient Led Oncology Hacking Cancer online portal.
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