New blood test can accurately detect 50 types of cancer before symptoms appear
Final results of a study of a blood test that can detect more than 50 types of cancer have shown that it is accurate enough to be deployed as a multi-cancer screening test in people at higher risk of the disease , including patients over the age of 50. or more, without symptoms.
In an article published in the leading journal on cancer Annals of Oncologytoday (Friday), researchers report that the test accurately detected cancer, often before symptoms appeared, while having a very low false-positive rate. The test also predicted the location of cancer in the body with a high degree of accuracy, which could help doctors choose effective diagnostic tests.
GRAIL, Inc. (California, US), the company that develops and funds the research, has now made the multi-cancer early detection test available in the US only by prescription, and in addition to other screening methods. existing ones such as those of the breast, cancers of the cervix, prostate, lung and intestine.
Many cancers the test is able to detect lack screening tests, such as cancers of the liver, pancreas and esophagus, which are among the deadliest and for which early detection could make a real difference.
Detecting cancer early, when treatment is more likely to be successful, is one of the most important opportunities we have for reducing the burden of cancer. These data suggest that, if used with existing screening tests, the multi-cancer detection test could have a profound impact on how cancer is detected and, ultimately, on public health. “
Dr Eric Klein, first study author and chair, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, USA
The test involves taking a sample of each patient’s blood and analyzing it for DNA, known as cell-free DNA (cfDNA), that tumors (and other cells) shed in the blood. Genomic sequencing is used to detect chemical changes in DNA called ‘methylation’ that control gene expression, and a classifier developed with machine learning (artificial intelligence) uses these results to detect abnormal methylation patterns suggesting the presence of cancer.
Moreover, the machine learning classifier can predict where in the body the cancer is. The results are available within ten working days from the moment the sample arrives at the laboratory.
The third and final sub-study of the Circulating Cell-free Genome Atlas (CCGA) study released today looked at the performance of the test in 2,823 people already diagnosed with cancer and 1,254 people without cancer. He detected cancer signals from over 50 different types of cancer and found that across the four stages of cancer (I, II, III, IV) the test correctly identified when cancer was present ( sensitivity or rate of true positives) in 51.5% of cases. case.
The specificity of the test (the rate of true negatives) was 99.5%, which means that the test incorrectly detected cancer (the rate of false positives) in only 0.5% of cases.
The sensitivity of the test was 67.6% overall for stages I-III in 12 pre-specified cancers that each year account for two-thirds of cancer deaths in the United States (anal, bladder, bowel, esophagus, stomach, head and neck, liver and bile duct, lung, ovarian and pancreatic cancers, lymphomas and white blood cell cancers such as multiple myeloma), and it was 40.7% in the together in more than 50 cancers.
For all cancers, detection improved at each stage of the cancer with a sensitivity rate of 16.8% in early stage I, 40.4% in stage II, 77% in stage III and 90.1% in stage IV – the most advanced stage where symptoms often appear.
Sensitivity varied depending on the type of cancer. In solid tumors that do not have screening options, such as cancers of the esophagus, liver, and pancreas, the overall sensitivity of the test was twice that of solid tumors that have screening options, such as breast, intestinal, cervical and prostate cancers: 65.6% against 33.7%. The overall sensitivity in blood cancers, such as lymphoma and myeloma, was 55.1%.
In addition, the multi-cancer early detection test correctly identified the tissue in which the cancer was located in the body in 88.7% of cases.
Dr Klein said: “We believe that cancers which release more cfDNA into the bloodstream are detected more easily. These cancers are also more likely to be fatal, and previous research shows that this multi-cancer early detection test more strongly detects these types of cancer. Cancers such as the prostate release less DNA than other tumors, which is why existing screening tests are still important for these cancers. “
In order to understand how the test would work when used to screen populations, the researchers estimated its positive predictive value (PPV) – the proportion of cases correctly identified as cancer among those with a positive result – as well as negative predictive value. (VPN) – those correctly identified as having no cancer. The PPV was 44.4% in those most likely to develop cancer, those aged 50 to 79, and the NPV was 99.4%.
Dr Klein concluded: “These data add to a growing body of literature that supports the use of next-generation sequencing for the detection of cell-free DNA in blood samples as a tool for the early detection of common cancers which represent a significant number of deaths and other health problems in the world.
In addition, a screening test that requires only a simple blood test could be an option for communities that have limited access to medical facilities. I am excited about the potential impact this approach will have on public health. “
Researchers continue to collect additional data on the test in large prospective studies in the United States (STRIVE, PATHFINDER and REFLECTION studies) and the United Kingdom (SUMMIT study), and to examine its feasibility for screening populations. GRAIL has also partnered with the UK’s National Health Service to study the clinical and economic performance of the multi-cancer early detection test in approximately 165,000 eligible patients, as of year-end.
One of the strengths of the CCGA study is that, overall, it includes a total of 15,254 participants from 142 clinics across North America, which helps ensure that the results can be generalized to a diverse population. Participants in this final substudy were not included in the early stages of test development to ensure accurate performance estimates.
The limitations of this substudy include: if blood samples were taken from cancer patients after they had undergone a biopsy, it could increase the proportion of cfDNA in the blood compared to before the biopsy; The CCGA is a case-control study and may not fully reflect the performance of the assay under population screening conditions (this is being evaluated in the PATHFINDER study); and some inaccuracies have occurred in the detection of cancerous tissue for cancers caused by human papillomavirus (HPV), such as cancers of the cervix, anus, and head and breast. neck.
Editor-in-chief of Annals of Oncology, Professor Fabrice André, Research Director at the Institut Gustave Roussy, Villejuif, France, said: “The early detection of cancer is the next frontier in cancer research because it could save millions of lives around the world. . The next steps will include the development of new therapeutic interventions. At the same time, major efforts related to sensitizing the population must continue or all these efforts will not lead to a transformation of the results.