New Blood Test Can Accurately Detect 50 Types Of Cancer Befo
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Final results from a study of a blood test that can detect more than 50 types of cancer have shown that it is accurate enough to be rolled out as a multi-cancer screening test among people at higher risk of the disease, including patients aged 50 years or older, without symptoms.

The test involves taking a sample of blood from each patient and analysing it for DNA, known as cell-free DNA (cfDNA), which tumours shed into the blood. Genomic sequencing is used to detect chemical changes to the DNA called methylation that control gene expression, and a classifier developed with machine learning uses these results to detect abnormal methylation patterns that suggest cancer is present.

In addition, the machine learning classifier can predict where in the body the cancer is located. Results are available within ten business days from the time the sample reaches the lab. The third and final sub-study of the Circulating Cell-free Genome Atlas (CCGA) study investigated the performance of the test in 2,823 people already diagnosed with cancer and 1,254 people without cancer.

It detected cancer signals from more than 50 different types of cancer and found that across all four cancer stages (I, II, III, IV), the test correctly identified when cancer was present (the sensitivity or true positive rate) in 51.5% of cases. The test's specificity (the true negative rate) was 99.5%, meaning that the test wrongly detected cancer (the false positive rate) in only 0.5% of cases.

Sensitivity of the test was 67.6% overall across stages I-III in 12 pre-specified cancers that account for two-thirds of cancer deaths in the USA each year, and it was 40.7% overall in more than 50 cancers. For all cancers, detection improved with each cancer stage with a sensitivity rate of 16.8% at the early stage I, 40.4% at stage II, 77% at stage III and 90.1% at stage IV - the most advanced stage when symptoms are often showing.

The sensitivity varied by type of cancer. In solid tumours that do not have any screening options, such as oesophageal, liver and pancreatic cancers, overall sensitivity of the test was twice that for solid tumours that do have screening options, such as breast, bowel, cervical and prostate cancers: 65.6% compared to 33.7%. Overall sensitivity in cancers of the blood, 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. 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 the negative predictive value (NPV) - those correctly identified as not having cancer. The PPV was 44.4% among people most likely to develop cancer, those aged 50-79, 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 earlier detection of common cancers that account for a significant number of deaths and other health problems worldwide.

Source:
https://www.annalsofoncology.org/article/S0923-7534(21)02046-9/fulltext
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