Largest Real-World ctDNA Study Doubles Detection of New Cancers

Largest Real-World ctDNA Study Doubles Detection of New Cancers
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A study using a single mutation-based screening blood test for multiple cancer types found it could detect asymptomatic cancers in women. In the Detecting cancers Earlier Through Elective mutation-based blood Collection and Testing (DETECT-A) study, 10,000 women ages 65 to 75 with no prior cancer history were evaluated using CancerSEEK, a liquid biopsy blood test based on detection of circulating tumor DNA (ctDNA) developed at Johns Hopkins University.

The DETECT-A study was the largest liquid biopsy study in a general population with no history of the disease, instead of in individuals with a previous cancer history or at known high-risk. Over the course of the study, 96 women developed cancer; 26 were first detected by the new blood test; 24 were identified with standard screening methods; 46 were detected by development of symptoms or other methods. Together, the blood test plus standard-of-care testing had a combined sensitivity of 52.1 percent, double the rate of standard screening alone.

During the first year of follow-up, conventional screening found breast, lung, and colon cancers in 24 women whose ctDNA blood test was negative. For this reason, the Hopkins team views its test as “additive and complementary” to standard screening, according to study co-leader Nickolas Papadopoulos.

However, 101 of the women who had a positive test and received follow-up imaging turned out not to have cancer; 22 of them underwent invasive tests such as an endoscopy.

Cancers were detected in ten different organs, including seven which do not have reliable screening protocols, including ovarian, kidney, lymphoma, appendix, uterine, thyroid, and cancers arising from an unknown primary site. Cancers initially detected by the blood test included cancers in 10 different organs: lymphomas (2), colorectal (2), appendix (1), uterine (2), thyroid (1), kidney (1), lung (9), breast (1), ovary (6) and unknown primary (1).

And, most of the cancers found by the blood test–17 of 26, or 65 percent —were detected at a localized or regional stage.

The study was a prospective interventional design. Neither study participants nor researchers were aware of the presence of cancer or cancer symptoms at the time of testing. The information learned from the study was provided to physicians to help design appropriate treatments.

The women in the DETECT-A Study were recruited from a larger population at Geisinger Health Systems with known high adherence to standard-of-care cancer screening tests, such as mammography and colonoscopy.

Of the 10,006 women initially enrolled between September 2017 and May 2019, 9,911 completed the study. Of the 95 people excluded from the study, 73 voluntarily withdrew, 12 were found to have a history of cancer and 10 did not complete the necessary clinical workup.

DETECT-A used a 2016 version of CancerSEEK blood test which probes for 16 genes and nine proteins associated with multiple types of cancer. In this study, if a woman’s test was positive for at least one of these markers, she was offered a second test. If that test appeared real, she was invited to undergo PET-CT imaging to confirm the diagnosis and receive appropriate treatment.

Blood testing followed by PET-CT imaging was 99.6% specific for cancer. The researchers also confirmed that the genetic mutations picked up by the blood test that led to a positive test were present in the cancer 100% of the time.

A secondary goal of the DETECT-A study was to show that blood testing could be integrated with conventional screening methods for detecting breast, colon and lung tumors. The researchers found that combined screening for these three cancers improved sensitivity from 47% to 71%.