Most cancers cannot be reliably diagnosed until symptoms begin. Although there are exceptions such as mammograms and pap smears, reliable screening methods do not exist for most cancers. To improve early cancer detection, dozens of companies have devised a test method that can detect various signs of cancer in blood taken from a patient’s arm. Now, to check how effective these early cancer screening blood tests are in practice, a national clinical trial is scheduled to begin in the United States.
In a speech held in Boston on the 12th, President Biden of the United States said that early diagnosis of various cancers using blood tests and clinical trials scheduled in the future are the ambitious plan for conquering cancer in the United States.Cancer Moonshot‘ was the key point. Cancer Moonshot is a federal plan to halve the number of cancer deaths in the United States over the next 25 years. President Biden’s speech this time was on the 60th anniversary of former US President John F. Kennedy’s announcement that he would send a man to the moon. The ‘Cancer Moonshot’ project was also inspired by the US moon exploration program.
The National Cancer Institute of the United States new clinical trialwill begin recruiting participants in 2024 and will examine 24,000 healthy participants over a four-year period to see how effective different blood test methods are in detecting cancer. If the clinical trial results look promising, the trial scale will be expanded 10 times and a large-scale clinical trial will start once more.
Most ‘multi-cancer early detection (MCED)’ tests work by finding the remains of tumor cells that are destroyed following the immune system attacks them. Remnants of dead tumor cells appear in the bloodstream, and even if the patient is asymptomatic, their presence may be a sign of cancer. After that, if cancer is confirmed by imaging tests, a biopsy is also performed.
There is only one type of multiple cancer early diagnosis (MCED) test currently in use in the United States. The Galleri test, which claims to detect early signs of more than 50 cancers, is available with a prescription for $949. However, most insurances do not cover the Galerie test, as it is not FDA-approved. Published by the developers of the Galerie test new dataAccording to The Galleri test, cancer was found in 35 of the 6,600 study participants believed to be healthy. In particular, 26 of them had cancer that was not diagnosed by regular check-ups.
Questions remain as to how to interpret the MCED test results. Only some blood tests can tell exactly where in the body the cancer actually originated. To confirm the diagnosis, laboratory tests of potentially cancerous tissue must be performed, but a biopsy of the entire body cannot be performed. False positives are also a problem in the entire field of cancer screening. The Galleri test, the MCED test closest to widespread use, also falsely labeled 57 healthy blood samples in the study mentioned above as having cancer.
There is also a risk that early diagnosis of cancer may lead to hasty action. Some cancers are unlikely to metastasize to other tissues or are not life-threatening, but early detection can make patients undergo very difficult treatments, such as chemotherapy. Fortunately, some studies suggest that this problem can be minimized because less-risk cancers actually appear less in the bloodstream.
The National Cancer Institute’s clinical trial will help determine how to interpret blood test results to diagnose cancer. It will also provide a guideline for how cancer screening research should be initiated, with multiple companies flooding the field with new testing methods.
Professor of Cancer Prevention at Harvard University Timothy Rebbeck“Most companies would not want to compare their test methods head-to-head with those of other companies,” he said. “It is a difficult and expensive task. So we need a neutral third party like the National Cancer Institute.”
Rebeck believes the blood tests to be confirmed in the new clinical trial will be most helpful for pancreatic, liver and ovarian cancers. These three cancers have a high mortality rate, but there is no early diagnosis. But even if blood tests are proven to be effective in diagnosing cancer early, longer-term clinical trials will be needed to determine whether the time saved by early diagnosis can actually save lives.
Still, Lebeck is optimistic regarding the ultimate goal of the Cancer Moonshot. “The idea of halving cancer mortality seems very realistic,” he said.
