Precision medicine is now a mainstay in cancer care, bringing to light the importance of genomic literacy among providers, according to Kate Reed, MPH, ScM, from The Jackson Laboratory in Bar Harbor, ME.Germline (inherited) and somatic (acquired) genomic variants can impact each step of a patient's cancer journey from diagnosis through the end of treatment. This vital information increases diagnostic specificity through the process of identifying tumor markers or a hereditary cancer syndrome, informs prognosis and risk of recurrence, and provides information about the need for adjuvant therapy and targeted treatment.
Germline genetics are hereditary cancer syndromes that explain why a person has cancer or increase a person's risk for developing cancer in the future. In testing for germline genetic variants, family history is crucial. Patients typically receive genetic counseling before and after testing to help them understand their personal risk for developing a certain type of cancer and its potential treatment options, and to decide whether they want that information.But the field is moving toward identifying the specific variants in a person's tumor cells that are driving its growth and targeting that mechanism. This growing area of genomics requires somatic testing, in which genomic and molecular tumor boards conduct a multidisciplinary review and interpretation of test results. "When faced with the test results, tumor boards help the oncologist to prioritize and understand the evidence behind these variants, and how they should use this information," she said at the AONN+ Midyear Conference. According to Ms Reed, these 2 testing processes are likely to be combined in the future, but currently they serve different purposes with different approaches. Genomic testing can be used after initial treatment in a variety of ways, and the findings can help patients prepare for future decisions. On the germline side, if a hereditary cancer syndrome is identified, a patient can receive counseling on surveillance and monitoring for recurrence/secondary cancers. They can also receive information about testing close relatives for the variant causing the syndrome, known as cascade testing. On the somatic side, liquid biopsy can differentiate cancer cells from noncancer cells in a blood sample. Once a person finishes treatment, continued surveillance of blood samples can pinpoint genomic variants associated with a certain cancer type and help to determine whether cancer cells are increasing in that individual over time. Additionally, if a large-panel genomic test previously identified actionable variants for targeted therapies, those may be called on in the case of a recurrence. But genomic information is only as good as the existing knowledge base, and the field is still relatively new, said Ms Reed. One challenge is tumor heterogeneity; on the genetic level, tumors are not all the same, and subsets of the tumor may have different genetic markers, bringing into question the reliability of the test results. Tests can also reveal variants of unknown significance on both the germline and the somatic sides, and to understand the role of these variants in the field of genomics, more clinical data are needed.
As with any treatment, genomic information is only as good as the ability to use it, she added. Challenges with patient access to clinical trials using these new targeted therapies and issues with off-label use call into question the widespread applicability of their benefits, underlining the need to set realistic expectations with patients who express hope for these treatments.
"There is a lot of promise with genomics, but we don't have all the answers yet," Ms Reed said. "It's complex, as is everything in oncology."