Cancer doctors, caregivers, and payers must brace themselves for a huge shift in early cancer detection that will affect practically every stage of cancer diagnosis and therapy.
According to Fabrice André, ESMO 2022 Scientific Co-Chair, new findings demonstrating the accuracy of multi-cancer early detection (MCED) blood tests presented at the ESMO Congress 2022 have substantial implications for future cancer care provision.
In-development MCED diagnostics can detect a common cancer signal from over 50 different cancer types and determine where the signal originated in the body. The signal comes from small pieces of circulating tumor DNA (ctDNA) in the blood that have methylation patterns that are different from those of normal DNA.
In the PATHFINDER study, which was presented at the ESMO Congress 2022, an MCED test found a cancer signal in 1.4% of 6621 people 50 and older who did not know they had cancer. In 38% of those with a positive test, the cancer was confirmed. 99.1% of the tests done on 6290 people who did not have cancer came back negative.
For people who had a positive test result, it took a median of 79 days to reach a diagnosis (i.e., to find cancer or decide there was no sign of cancer that needed more testing). 73% of participants with a positive screening test had their diagnostic issue resolved within three months.
“The results are an important first step for early cancer detection tests,” says study senior author Deb Schrag, adding “because they showed a good detection rate for people who had cancer and an excellent specificity rate for those who did not have cancer.
“In people with a positive test,” as explained by the author, “it took less than two months to confirm the diagnosis if they had cancer and it took a bit longer if they did not have cancer primarily because physicians opted to perform imaging studies and then repeat them a second time several months later to investigate the possibility of a cancer diagnosis.”
“An important finding,” according to Schrag, “was that few participants with a false positive screening test required multiple invasive procedures such as endoscopies and biopsies. This finding should help to allay concerns that these tests could cause harm by generating unnecessary procedures in people who are well.”
While MCED tests are being developed and validated for malignancies including pancreatic, small intestinal, and stomach cancer where there are currently no screening alternatives, she emphasized the need of continuing routine screening for tumors like breast and colorectal cancer.
This study suggests that there is potential for the detection of tumors that are currently undetectable, but obviously much more effort is needed, and these tests will get better with practice and larger samples. According to Schrag, the tests must be improved in order to better identify tumor DNA from all the other DNA that is circulated in the blood. It is also crucial to remember that the goal of cancer screening is to reduce cancer mortality rather than cancer incidence. Since mortality was not assessed in the PATHFINDER trial and necessitates extensive follow-up, it is premature to draw any conclusions on how MCED testing influences mortality.
Since previous research only used tests on people who already knew they had cancer, the study presented at the ESMO Congress 2022 is the first prospective study to show that an MCED test can find cancer in people who don’t know they have it.
More research is currently being conducted, including a significant randomized clinical trial that will enrol 140,000 asymptomatic individuals in England to examine the therapeutic usefulness of MCED testing on cancer outcomes.
“We need comparative trials across all types of cancer to find out if having an early detection test affects morbidity and mortality. We also need to know how the tests benefit patients, and how to discuss the results with them,” adds André.
“In addition, we need to know more about the small proportion of false positive tests – MCED results that indicate cancer is present but this is not confirmed by standard diagnostic procedures. We need some of these answers before we can calculate the cost impact of introducing MCED tests in routine clinical practice,” André concludes.
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