Introduction

Earlier detection is key to reducing cancer deaths (1)(2). Many cancers can be cured by surgery or systemic therapies when detected before they have metastasized (2). This clinical reality, coupled with the growing appreciation that cancer’s rapid genetic evolution limits its response to drugs, have fueled interest in methodologies for earlier detection of the disease.

The majority of localized cancers can be cured by surgery alone, without any systemic therapy (2). Once distant metastasis has occurred, however, surgical excision is rarely curative. One major goal in cancer research is therefore the detection of cancers before they metastasize to distant sites (2). For many adult cancers, it takes 20 to 30 years for incipient neoplastic lesions to progress to late-stage disease (2)(3). Even when metastasis has initiated but is not yet evident radiologically, cancers can be cured in up to 50% of cases with systemic therapies, such as cytotoxic drugs and immunotherapy (2)(3). Once large, metastatic tumors are formed, however, current therapies are rarely effective (2)(3).

What is currently used?

The only widely used blood test for earlier cancer detection is based on measurement of prostate-specific antigen, and the proper use of this test is still being debated (2). The approved tests for cancer detection are not blood-based and include colonoscopy, mammography, and cervical cytology (1)(2). New blood tests for cancer must have very high specificity; otherwise, too many healthy individuals will receive positive test results, leading to unnecessary follow-up procedures and anxiety (2)(3).  Blood tests that detect somatic mutations (liquid biopsies) offer the promise of exquisite specificity because they are based on driver gene mutations that are expected to be found only in abnormal clonal proliferations of cells, such as cancers (2)(3). Yet another issue with liquid biopsies is the identification of the underlying tissue of origin. Because the same gene mutations drive multiple tumor types, liquid biopsies based on genomic analysis alone generally cannot identify the anatomical location of the primary tumor.

What did the scientists discover?

Johns Hopkins Kimmer Cancer Center researchers developed a single blood test that screens for eight common cancer types and helps identify the location of the cancer (2)(3)(4). The test is called CancerSEEK(2). It is a unique noninvasive, multianalyte test that simultaneously evaluates levels of eight cancer proteins (that account for more than 60 percent of cancer deaths in the U.S(2)(3)(5). Five of the cancers covered by the test currently have no screening test) and the presence of cancer gene mutations from circulating DNA in the blood (3)(4).

Figure 1. CancerSEEK test. Image adapted from (5).

CancerSEEK being noninvasive can be administered by primary care providers at the time of other routine blood work (2)(3)(4). Earlier detection provides many ways to improve outcomes for patients (4)(5). Optimally, cancers would be detected early enough that they could be cured by surgery alone, but even cancers that are not curable by surgery alone will respond better to systemic therapies when there is less advanced disease according to Anne Marie Lennon, M.D., Ph.D.,associate professor of medicine, surgery and radiology, clinical director of gastroenterology and director of the Multidisciplinary Pancreatic Cyst Program (2). The investigators feel that a test that will be used routinely for cancer screening must have a cost in line with or less than other currently available screening tests for single cancers, such as colonoscopy (2)(3)(4). They envision that the CancerSEEK test will eventually cost less than $500 (3)(4).

Figure 2. Colored curves indicate the proportion of cancers of the eight types evaluated in this study that can be detected with an increasing number of short (<40 bp) amplicons. The sensitivity of detection increases with the number of amplicons but plateaus at ~60 amplicons. Colored dots indicate the fraction of cancers detected by using the 61-amplicon panel used in 805 cancers evaluated in our study, which averaged 82%. Publicly available sequencing data were obtained from the COSMIC repository. Image adapted from (2).

Figure 3. Performance of CancerSEEK.(A) ROC curve for CancerSEEK. The red point on the curve indicates the test’s average performance (62%) at >99% specificity. Error bars represent 95% confidence intervals for sensitivity and specificity at this particular point. The median performance among the eight cancer types assessed was 70%. (B) Sensitivity of CancerSEEK by stage. Bars represent the median sensitivity of the eight cancer types, and error bars represent standard errors of the median. (C) Sensitivity of CancerSEEK by tumor type. Error bars represent 95% confidence intervals.Image adapted from (2).

COPYRIGHT: This article is the property of We Speak Science, a non-profit institution co-founded by Dr. Detina Zalli.The article is written by Dr. Detina Zalli (Harvard University).

References

  1. Stephen L. Hauser, Dennis L. Kasper, MD, Anthony S. Fauci, MD, Dan L. Longo, MD, J. Larry Jameson MD, phd, Dan L. Longo, MD, Joseph Loscalzo, MD, phd (2015). Harrison’s principles of internal medicine; Hematology and Oncology. 19th edition. Mcgraw-Hill Education
  2.   Joshua D. Cohenet al. Detection and localization of surgically resectable cancers with a multi-analyte blood test. 23rdFebruary. Science. Retrieved December 20,2018 fromhttp://science.sciencemag.org/content/359/6378/926
  3. Honor Whiteman. (2018, January 19). Eight cancers could be diagnosed with a single blood test. Medical News Today. Retrieved December 20, 2018 from https://www.medicalnewstoday.com/articles/320679.php
  4. Johns Hopkins Medicine. (2018, January 18). Single blood test screens for eight cancer types: Provides unique new framework for early detection of the most common cancers. ScienceDaily. Retrieved December 20, 2018 from sciencedaily.com/releases/2018/01/180118141803.htm
  5. Johns Hopkins Medicine. (2018, January 18). Single blood test screens for eight cancer types. Johns Hopkins Medicine. Retrieved December 20, 2018 from https://www.hopkinsmedicine.org/news/newsroom/news-releases/single-blood-test-screens-for-eight-cancer-types