The increased interest in liquid biopsy tests for circulating tumor biomarkers does have the potential to revolutionize cancer diagnostics. However, certain limitations still exist for the liquid biopsy test. Many of these limitations tend to minimize its widespread acceptance and usage within the medical community combined with the limited support for the test by major insurers and professional organizations.
As presented earlier in this course, the main limitations to the liquid biopsy test include the following:
- The current gold standard for confirmation and diagnosis of cancers is still the tissue biopsy. Hence, the liquid biopsy is not yet a replacement for the tissue biopsy but is mainly being used as a complementary test to the tissue biopsy.
- There is currently not a widespread usage for liquid biopsy within the medical community. More support for the clinical utility of the liquid biopsy is needed. More validation in clinical trials is required on the value of liquid biopsies in the medical setting to support the clinical utility of the test.
- More studies are needed to assess the test’s accuracy and its ability to identify various tumor types.
- Test sensitivity challenges still exist. Given that circulating tumor cells or DNA are relatively rare compared to the number of hematological molecules found in a blood sample, there are challenges to the test’s detection ability, i.e. the sensitivity of the liquid biopsy test.
Even with these limitations and challenges facing the liquid biopsy test, there are currently a substantial and growing number of companies involved in the development of liquid biopsy tests. This substantial level of involvement does suggest that many experts believe the liquid biopsy will be a valuable modality in cancer research and diagnostics. Moreover, various clinical trials are underway to determine if liquid biopsy testing for cancer-specific biomarkers or mutations in the circulation can have clinical use for the early diagnosis of cancer and to assist in the improvement of patient treatment and outcomes.
In summary, the liquid biopsy test is now being used more as a complementary test to tissue biopsy, or used when tissue biopsy is difficult to obtain, or the tissue specimen is inadequate. Its value appears to be in serial monitoring for cancer progression and in assessing the therapeutic benefits of a given therapy.
