FDA approves first blood test to detect colorectal cancer

On July 29, the U.S. Food and Drug Administration (FDA) approved Guardant Health’s Shield™ test, the first colorectal cancer screening test that analyzes a blood sample to identify molecular signs of cancer. The latest research shows that early detection of cancer improves treatment outcomes and survival rates and experts predict that having a non-invasive option will help to screen more patients and catch colorectal cancer at treatable stages. At Private Health Management (PHM), our experts stay up to date on the latest developments in cancer screening and help guide our clients in choosing the screening methods that are right for them.

Colorectal cancer screening is essential
Colorectal cancer is the second-leading cause of cancer deaths in the U.S. and the incidence of colorectal cancer is on the rise in younger patients. Recent data show that colorectal cancer is the leading cause of cancer-related deaths in men under 50 and ranks second in women under 50.¹ While diet and lifestyle are being linked to this rise, the exact risk factors are unknown. These trends highlight the importance of colorectal cancer screening and have resulted in revised guidelines that have lowered the starting age for screening from 50 to 45 years of age.^2–4

The American Cancer Society’s estimates for the number of colorectal cancers in the United States for 2024 are:

• About 106,590 new cases of colon cancer (54,210 in men and 52,380 in women)
• About 46,220 new cases of rectal cancer (27,330 in men and 18,890 in women)

To date, colorectal screening tools have included imaging-based tests that directly examine the colon and rectum for signs of abnormalities (colonoscopy, CT colonoscopy, flexible sigmoidoscopy) and non-invasive tests that detect signs of colorectal cancer in stool samples.^2–4 But, studies show that over 50 million eligible patients have not undergone screening, as many perceive conventional screening options as invasive, unpleasant, or inconvenient.⁵ Having a non-invasive, blood-based test is expected to improve screening rates.

Blood-based colorectal screening with Shield^TM
Shield™ has been approved as a primary colorectal cancer screening tool for individuals aged 45 and over who are at average risk and have no family history and no symptoms.⁶ The cost of Shield™ testing has not been announced, but the test meets the requirements for Medicare coverage.

The Shield™ test is performed on a blood sample and does not require time for advanced preparation or time away from work or family, like some traditional screening tests. Shield™ identifies colorectal cancer-related signals, including DNA mutations and alterations, as well as changes in patterns of DNA methylation, which can affect gene regulation and influence tumor growth. If a patient receives a positive Shield™ test for colorectal cancer signals, the next step is to have a colonoscopy to verify the result and remove any polyps for further laboratory testing.

Clinical studies have shown that Shield™ is highly accurate in detecting stage II-IV colorectal cancers. However, the FDA cautioned that Shield™ has limited ability to detect precancers and stage 1 cancers, as data show that it does not detect 87% of precancerous lesions, and 10% of patients who receive a negative test may have a precancer that could have been detected by colonoscopy. The overall sensitivity and specificity are comparable to stool-based tests; however, stool-based tests exhibit a higher sensitivity for precancerous and stage 1 cancers.

There are several other blood-based cancer screening tests in the market, including other single cancer tests, like FirstLook® by Delfi Diagnostics for those at high risk of lung cancer and multi-cancer early detection tests (MCED), like Galleri® by Grail, that can detect over 50 types of cancer in the bloodstream.
Choosing the right colorectal cancer screening option for you involves considering many factors, such as your family history, lifestyle risk factors, age, and more. At PHM, we strongly support following cancer screening guidelines and advocate for all patients to have access to screening. Your primary healthcare provider can help advise you on when to screen and what type of test is best to proceed.

References

1. 2024 Cancer Facts & Figures Cancer | 2024–First Year the US Expects More than 2M New Cases of Cancer. https://www.cancer.org/research/acs-research-news/facts-and-figures-2024.html.
2. Cancer Screening Guidelines | Detecting Cancer Early. https://www.cancer.org/cancer/screening/american-cancer-society-guidelines-for-the-early-detection-of-cancer.html.
3. Detection, Prevention, and Risk Reduction. NCCN https://www.nccn.org/guidelines/category_2.
4. A and B Recommendations | United States Preventive Services Taskforce. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation-topics/uspstf-a-and-b-recommendations.
5. Shaukat, A. & Levin, T. R. Current and future colorectal cancer screening strategies. Nat Rev Gastroenterol Hepatol 19, 521–531 (2022).
6. Guardant Health, Inc. Shield colorectal cancer screening test. Provider brochure. https://shieldcancerscreen.com/wp-content/uploads/LBL-000351-R1-Shield-Provider-Labeling.pdf.