What Cancers Does the Galleri Test Detect? A Comprehensive Guide

Early detection is one of the most effective strategies in the fight against cancer. While traditional screening tests, like mammograms and colonoscopies, target one cancer type at a time, newer tools like the Galleri test take a broader, more proactive approach. Developed by GRAIL, the Galleri test is a multi-cancer early detection (MCED) blood test designed to screen for a signal shared by more than 50 types of cancer, many of which have no routine screening options today.¹

This matters because only about 5 of the more than 100 known cancer types have a recommended screening test, and roughly 70% of cancer deaths are caused by cancers with no recommended screening at all.²³

In this guide, we cover the cancers Galleri screens for, who it's for, how it works, how accurate it is, and how it fits into a modern preventive-health strategy.

The Galleri test is a blood test that screens for many types of cancer at once by detecting DNA fragments shed by tumors into the bloodstream, known as cell-free DNA (cfDNA).¹ Using methylation pattern recognition and machine learning, Galleri looks for a cancer signal and, when one is found, predicts where in the body the signal likely originated, called the Cancer Signal Origin (CSO).¹

Unlike standard tools that focus on one cancer at a time, Galleri offers a broader view. It's intended for adults 50 and older or those at elevated risk, and it's not designed for people who have symptoms of cancer, are currently undergoing cancer treatment, are pregnant, or are 21 or younger.⁴

Galleri screens for a signal shared by 50+ cancer types, including many with no standard screening protocol. In clinical studies, the following cancers were diagnosed after a "Cancer Signal Detected" result. Diagnostic testing is always needed to confirm cancer.¹

• Head, neck, and respiratory: larynx; nasal cavity and paranasal sinuses; nasopharynx; oropharynx (p16−) and hypopharynx; oropharynx (HPV-mediated, p16+); soft tissue sarcoma of the head and neck; oral cavity; lung; malignant pleural mesothelioma

• Reproductive and urinary: uterus (carcinoma, carcinosarcoma, sarcoma); vulva; cervix; gestational trophoblastic neoplasms; vagina; testis; penis; prostate; ovary, fallopian tube, and primary peritoneum; kidney; bladder; ureter and renal pelvis; adrenal cortical carcinoma

• Digestive and gastrointestinal: esophagus and esophagogastric junction; stomach; exocrine pancreas; ampulla of Vater; gastrointestinal stromal tumor (GIST); bile ducts; gallbladder; liver; colon and rectum; small intestine; anus; appendix

• Skeletal, soft tissue, and neuroendocrine: bone; soft tissue sarcoma (abdomen and thoracic visceral organs, retroperitoneum, trunk and extremities, unusual histologies); neuroendocrine tumors (appendix, colon and rectum, pancreas)

• Breast and skin: breast; melanoma of the skin; Merkel cell carcinoma

• Blood and lymphatic: leukemia; lymphoma (Hodgkin and non-Hodgkin); plasma cell myeloma and plasma cell disorders

Galleri is especially sensitive to several of the deadliest cancers that are often caught late. In clinical studies, overall sensitivity was about 83.7% for pancreatic cancer, 93.5% for liver and bile duct cancer, and 83.1% for ovarian cancer.¹

Galleri is built to keep false alarms very low. It has a false-positive rate of about 0.4% (roughly 99.5% specificity), meaning people without cancer rarely receive a "Cancer Signal Detected" result.¹⁵ Among people who do get that result, the positive predictive value is about 62%, meaning roughly 6 in 10 are confirmed to have cancer after diagnostic follow-up.⁶ When a signal is found, Galleri predicts the cancer's origin with about 93.4% accuracy, which helps guide an efficient work-up.⁶

Sensitivity, the ability to detect cancer that is present, increases with stage¹:

• Stage I: ~17%

• Stage II: ~40%

• Stage III: ~77%

• Stage IV: ~90%

Across the 12 cancers responsible for about two-thirds of U.S. cancer deaths, sensitivity is over 70%.¹ In practical terms, adding Galleri to standard screening for breast, cervical, colorectal, and lung cancer has been shown to increase the number of cancers detected several-fold.⁶ This means Galleri is strongest at catching later-stage and hard-to-screen cancers, and is meant to add to, not replace, routine screening.

No test catches everything. Galleri may miss cancers that shed little or no cfDNA, such as some brain cancers or very early, small tumors.¹ Sensitivity is also lower for certain cancers, like early-stage melanoma, bladder, and kidney cancer. Importantly, a "No Cancer Signal Detected" result does not guarantee you're cancer-free, which is why Galleri is designed to complement standard screening rather than replace it.⁷

Galleri is intended for adults at elevated risk of cancer, including⁴:

• Adults 50 and older

• People with a

  family history of cancer

• Those with elevated genetic or lifestyle risk

It is not recommended for people who⁴:

• Are 21 or younger

• Are pregnant

• Have symptoms of cancer

• Are currently undergoing cancer treatment

The process is straightforward⁴:

1. A healthcare provider orders the test.

2. A blood sample is collected.

3. The sample is analyzed in a CLIA-certified laboratory.

4. Results are delivered in a few weeks.

There are two possible results:

• Cancer Signal Detected:

  cfDNA associated with cancer was identified, along with a predicted Cancer Signal Origin. This requires

  confirmatory diagnostic testing

  .

• No Cancer Signal Detected:

  no cancer signal was found, though this does not rule out cancer entirely.

No. Like other MCED tests, Galleri is offered as a lab-developed test. GRAIL's laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA) and accredited by the College of American Pathologists, and the test's performance was established by GRAIL. It has not been cleared or approved by the FDA.¹ This is standard for this category of testing and does not mean the test is unproven; Galleri has been studied in more than 20,000 participants and published in peer-reviewed journals including the Lancet and Annals of Oncology.¹⁶

Galleri does not replace mammograms, colonoscopies, Pap tests, PSA tests, or low-dose CT scans. Instead, it complements them, especially for cancers that have no screening option at all.¹ Think of it as an added layer, not a substitute for the screenings your provider already recommends.

As with any emerging technology, MCED testing has prompted thoughtful debate. Critics point to the potential for overdiagnosis, anxiety from false positives, and unnecessary follow-up procedures.⁸ Supporters note Galleri's very low false-positive rate and high positive predictive value, and ongoing interventional studies continue to refine how these tests are best used to catch cancer earlier while minimizing harms.⁶

Galleri is not specifically designed to detect thyroid cancer, though it may pick up signals from nearby head and neck cancers.¹

Yes. Prostate cancer is among the detectable types, but Galleri should not replace PSA testing.¹

Yes. Galleri can detect certain blood cancers, including plasma cell myeloma.¹

Approximately $949. Most insurance plans do not currently cover it.⁴

Generally once a year, but frequency should be discussed with your healthcare provider.⁴

The Galleri test is an exciting advance in cancer detection, offering screening insight for many cancers that would otherwise go unnoticed until later stages. It isn't a replacement for routine screenings, and limitations remain, especially for early-stage detection. Talk with your healthcare provider about whether Galleri fits your preventive-health strategy.

Early detection is key to catching cancer at more treatable stages. Everlywell offers a range of at-home lab tests and virtual care visits to support your wellness journey. You can order the Galleri Multi-Cancer Early Detection Test through Everlywell, and we now also offer the Caris Detect Multi-Cancer Early Detection Test, another blood-based option that screens for a signal shared by 50+ cancers, with genetic counseling to help you understand your results. Your provider can help you decide which approach best fits your history and goals.

If you want to talk more about your specific risk factors and recommendations, you can schedule a virtual care visit with one of our credentialed healthcare providers.