Early cancer detection leads to increased survival, improved quality of life, reduced treatment costs, and decreased clinical outcomes. The advent of blood-based screening will help reduce the incidence of advanced disease and, ultimately, cancer mortality, speakers at the recent 2022 Pri-Med East Conference in Boston shared their thoughts on the benefits of blood-based screening on multi-cancer early detection and associated challenges.
Three speakers in the panel included Aparna R. Parikh, MD, Assistant Professor of Medicine, Harvard Medical School, Director of the MGH Cancer Center’s Global Cancer Care Program Massachusetts General Hospital Cancer Center; Charles Vega, MD, FAAFP, Health Sciences Clinical Professor UC Irvine Department of Family Medicine Assistant Dean for Culture and Community Education UC Irvine School of Medicine; Eric Klein, MD Emeritus Professor and Chair, Glickman Urological and Kidney Institute, Cleveland Clinic Fellow, Stanford University Distinguished Careers Institute, Stanford University, Palo Alto, CA.
Challenges of cancer screening in primary care
Barriers to cancer screening lead to higher mortality rates. These patient-associated barriers include lack of regular source of care, long travel distance to screening sites, no health insurance, low income, low health literacy, lack of transportation to a medical facility, lack of paid medical leave, and bias/mistrust among communities of color against healthcare providers.
Early cancer detection: the risks and benefits
The potential benefits of early cancer screening include reduced incidence of advanced disease and reduced cancer mortality. However, the risks include adverse events, false-positive results, false-negative results, anxiety, overdiagnosis and overtreatment, and increased cost.
Blood-based screening: a promising tool for early cancer detection
Multi-cancer early detection (MCED) is emerging as a promising tool to improve cancer screening in the primary care setting. It can screen multiple cancers by analyzing blood that carries a range of biomarkers, such as cell-free DNA/RNA, proteins, circulating tumor cells, exosomes, and tumor-educated platelets.
The criteria for evaluating MCED testing include high sensitivity/specificity, predicting of origin, thereby reducing “diagnostic odyssey,” detecting primarily lethal cancers to minimize overdiagnosis, validation with population-scale studies with large control groups, and cost-effectiveness.
The current state of MCED
Primary care clinicians should be aware that none of the MCED tests are FDA-approved, but one test is available to patients through a prescription. This test called Galleriâ developed by Grail is recommended for patients 50 years and older with or without additional cancer and is designed to be used in addition to guideline-recommended cancer screenings.
Benefits of MCED implementation
MCED has a higher specificity for cancer detection than currently recommended screening tests. MCED can detect cancers for which there are no current standardized screening guidelines (which make up 71% of cancer deaths) and reduce cancer mortality by early detection of cancers, that would otherwise only be detected at later stages. Successfully implemented MCED tests will improve patient outcomes by lowering late-stage (stage III and IV) cancer incidence by 78%, reducing 5-year cancer mortality by 39%, and reducing 26% of cancer-related deaths.
Challenges and considerations of MCED implementation
There are certain challenges to the execution of MCED. These include the availability of only one MCED test by prescription, timing and frequency of MCED tests, logistics of training clinicians to interpret results, lack of insurance coverage, and further data on validity and utility needed for MCED tests. Moreover, MCED does not replace current screening methods, and a negative MCED test does not rule out cancer.
MCED: A future treatment
As current cancer screening guidelines only address a few cancer types and many barriers exist in discussing and scheduling cancer screenings, blood-based MCED offers an impressive alternative as it can extend screening to all cancer types and increase access to screening. However, MCED must be done in conjunction with currently recommended screenings.
In the short term, MCED may benefit individuals with a higher risk of cancer, with a strong family history of cancer, smokers, known genetic carriers, pediatric cancer survivors, immunosuppressed individuals, or cirrhosis patients. In the long term, the general population over 50 can benefit from MCED.