Cancer Precision Medicine

Revolutionizing Cancer Detection: The Potential of Blood Tests

Jessie Xu—McMaster Life Sciences 2025

Cancer is a leading cause of death globally, accounting for nearly 10 million deaths in 2020, or nearly one in six deaths1. Cancer results from the uncontrollable division of abnormal cells. The most common cancer are breast, lung, colon and rectum, and prostate cancer1. While the survival rate varies depending upon the types of cancer, the chance of survival is significantly greater when cancer is diagnosed earlier. In general, the rate of survival of cancer is 91% when diagnosed at an early stage, and 26% when diagnosed at a later stage7. However, recently scientists have proposed the use of blood tests to diagnose various types of cancer. Blood testing is quick and non-invasive, relatively inexpensive, and readily available. Currently available cancer blood tests include Complete blood count (CBC), CancerSEEK Test, Galleri multicancer early detection (MCED) test and PanSeer Test. 

Complete blood count (CBC)

SOURCE: Verywell Health

CBC is a common blood test used to detect a variety of disorders. The results of the CBC can be used to direct one’s diagnosis towards a particular disease2. Moreover, this test can be used to detect Blood Cancers, such as leukemia and lymphoma3.

CancerSEEK Test

SOURCE: Dr. Lal PathLabs Blog

The CancerSEEK Test detects cell-free DNA, cfDNA, and identifies eight biomarkers released by Tumour cells4. This blood test can detect the problems in the early stage of tumor5. Tumors are detected by mutations in genomic positions, such as substitutions, insertions and deletions4. So far, eight types of cancer can be detected with over 99% accuracy, including ovarian, liver, stomach, pancreatic, esophageal, colorectal, breast, and lung4.

Galleri multicancer early detection (MCED) test

SOURCE: Johns Hopkins Medicine Newsroom

The Galleri MCED is a novel, high-performance genomic technology that can detect signals from Cancerous cells at the early stage6. The Galleri MCED test aims to identify cfDNA circulating in the blood, and specifically recognized DNA methylation. The test result can indicate the specific type of cancer, and identify in which organ cancerous cells are present4. There are 12 types of cancer at the early stage that can be detected with 93% accuracy, including anorectal, colorectal, esophageal, gastric, head and neck, hormone receptor-positive breast, liver, lung, ovarian, and pancreatic cancers, in addition to multiple myeloma and lymphoid neoplasms4.

PanSeer Test

SOURCE: Galleri for HCPS

The PanSeer test uses a similar approach to the Galleri MCED test. This test was developed by the Taizhou Longitudinal Study that compared blood samples of individuals with and without cancer. In this study, they compared approximately 400 blood samples with cancer and approximately 400 blood samples without cancer. After that, they record physical measurements and questionnaires about the cancer occurrence, collecting affectional plasma and tissue samples at 3-year intervals7. The test detected patterns of DNA methylation, and 95% of asymptomatic individuals were diagnosed with cancer by using standard detection methods4. However, this test is unable to determine the exact location of the cancer4.

Overall, although blood tests can be used to detect cancer at the early stage which increases the rate of survival, not all types of cancer can be detected. In addition, some confounding factors, such as personal lifestyle, environmental pollution, and individual genetic composition, would make it difficult to develop standardized blood tests for all individuals7.


1. Cancer [Internet]. World Health Organization. World Health Organization; 2022 [cited 2023Jan2]. Available from: 

2. Complete blood count (CBC): Medlineplus medical test [Internet]. MedlinePlus. U.S. National Library of Medicine; 2022 [cited 2023Jan1]. Available from: 

3. Understanding your complete blood count (CBC) tests [Internet]. Cancer.Net. 2019 [cited 2023Jan1]. Available from: 

4. Tomasz BM. Novel blood-based early cancer detection: Diagnostics in development [Internet]. AJMC. MJH Life Sciences; 2020 [cited 2023Jan1]. Available from: 

5. Kuppuraj G. Cancerseek: A single blood test for early detection of eight cancer types – prescouter – custom intelligence from a global network of experts [Internet]. PreScouter. 2018 [cited 2023Jan2]. Available from: 

6. Hackshaw A, Clarke CA, Hartman A-R. New Genomic Technologies for multi-cancer early detection: Rethinking the scope of cancer screening [Internet]. Cancer Cell. Cell Press; 2022 [cited 2023Jan2]. Available from: 

7. Chen X, Gole J, Gore A, He Q, Lu M, Min J, et al. Non-invasive early detection of cancer four years before conventional diagnosis using a blood test [Internet]. Nature News. Nature Publishing Group; 2020 [cited 2023Jan2]. Available from: 

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