Exact Sciences, the maker of Cologuard, is now marketing Cancerguard, a blood-based multi-cancer early detection (MCED) assay. CancerGuard is designed for adults aged 50 to 84 years as a complement to existing routine screening. The test utilizes a blood-based approach to identify molecular signatures associated with malignancy. Specifically, the assay detects alterations in circulating tumor DNA (cfDNA) methylation patterns and measures various tumor-associated protein levels. The test is intended to identify more than 50 cancer types and subtypes, particularly those for which no standard-of-care screening currently exists.

CancerGuard's accuracy was established in an independent, case-control clinical validation study (N=1,124), which included 324 participants with active cancer and 800 non-cancer participants. When excluding breast and prostate cancers (which the test is not indicated for), the overall sensitivity was 55.6% (95% CI: 49.0%–62.0%) and the specificity was 97.4% (95% CI: 96.0%–98.3%). Sensitivity was highly dependent on the clinical stage of the cancer: Stage I sensitivity was 26.8% (95% CI: 17.0%–39.6%), Stage II was 42.9% (95% CI: 30.8%–55.9%), Stage III was 63.6% (95% CI: 50.4%–75.1%), and Stage IV was 89.3% (95% CI: 78.5%–95.0%). Based on these validation data, the test has a positive predictive value (PPV) of 17.8% for a general population aged 50–85 years with an undiagnosed cancer prevalence of 1%. This means that 82.2% of positive test results are false positives. See the Cancerguard fact sheet for detailed performance tables.

Results are reported qualitatively as either a "positive" or "negative" cancer signal; individual biomarker levels are not disclosed. For patients with a positive test result, a standardized diagnostic pathway is recommended to localize the potential malignancy. This follow-up includes a CT scan of the neck, chest, abdomen, and pelvis with iodine-based IV contrast. If the initial CT findings are negative or indeterminate, clinicians are advised to proceed with a whole-body 18F-FDG PET-CT to investigate the signal further.

The CancerGuard test can be ordered through paper requisition forms, integrated Electronic Medical Record (EMR) systems, or online via the Exact Sciences Provider Hub or EpicCare Link. Specimen collection requires four LBgard blood tubes, totaling 34 mL of whole blood, which must be shipped for processing on the same day as collection using FedEx Priority Overnight. The specimens must be processed at the laboratory within 72 hours of draw. Currently, the test is not covered by health insurance. The self-pay price is $689, though the cost may be eligible for HSA/FSA. Exact Sciences also offers an imaging reimbursement program to assist eligible patients with out-of-pocket costs for follow-up diagnostic imaging.

Important considerations to discuss with patients who are interested in the CancerGuard test include:

• The test misses almost half of cancers
• Most positive tests will be false positives
• Test results are reported as positive or negative only; individual biomarker levels are not disclosed. This can be anxiety-provoking for patients and makes formulating a diagnostic workup difficult.
• Insurance companies may decline reimbursement for follow-up imaging

• Cancerguard website
• Cancerguard fact sheet