The Search for Blood-Based Cancer Detection

Gene Yang ‘19

Figure 1. CancerSEEK aims to utilize DNA and protein biomarkers found in the blood to screen for eight different types of cancer.

A large number of cancer diagnoses are made when the cancer has metastasized and is no longer curable. In order to aid in preventing this from occuring, researchers are currently working on methods of early cancer detection. One such method, CancerSEEK, was created by scientists at John Hopkins University and other institutions. CancerSEEK is a liquid biopsy—a test done on a sample of blood—that takes advantage of recent developments in the field of blood molecular analysis involving liquid biopsy.

The first step of this procedure involves the analysis of circulating cell-free DNA (cfDNA) which, relative to normal DNA, can be easily extracted and sequenced from blood samples. Most cfDNA are small fragments of DNA that originate from normal tissue, but cfDNA, which comes from cancer tissue, can be often distinguished by the presence of characteristic mutations. However, it is impossible to distinguish which type of tissue the cfDNA came from, and thus, accurate cancer diagnoses cannot be made with cfDNA sequencing alone.

CancerSEEK combines cfDNA sequencing with another biomarker: a class of proteins known as tumor-associated serum proteins. Tumor-associated serum proteins and cfDNA alone make for unreliable cancer biomarkers, but when testing is combined, a more accurate probabilistic model for cancer can be developed. This algorithm was tested on 1005 patients, and resulted in 33% to 98% accurate cancer diagnoses, depending on the type of cancer. Notably, CancerSEEK is one of the few general blood-based methods that is able to detect specific types of cancer. While CancerSEEK is a step forward in the field of blood cancer biomarkers, more research will be needed for early cancer detection methods to become truly effective.


  1. J. Cohen, et al., Detection and localization of surgically resectable cancers with a multi-analyte blood test. Science 359, 866-867 (2018) doi:10.1126/science.aar3247.
  2. Image retrieved from:

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