already available (only by prescription and for a fee) in the US, but experts warn: We are a long way from real use in healthy people. Here’s why
In the scientific journal Annals of Oncology the results of a very promising experiment have been published: a group of American scientists has in fact developed the first blood test capable of accurately recognizing over 50 types of cancer and identifying in which tissue (or organ) the tumor originates , before the disease gives clinical signs of its presence. Identify a tumor in the very early stages, perhaps even before it is visible in the exams available today or that manifests itself with some symptoms, the goal on which hundreds of researchers around the world work. The stakes are very high because, the smaller and more circumscribed the neoplasm, the greater are the chances of completely healing and succeeding with minimally invasive and toxic therapies. Many steps forward have been made in this direction in recent years, thanks to advances in scientific research and new sophisticated technologies, but caution is still needed and the news that periodically arrives (especially from the United States) must be weighed bearing in mind both the understandable enthusiasm of scientists. who develop these tests, both the economic interests of the companies that produce and sell them at a cost that is around several thousand euros each.
The final data of the experiment, recently announced on Annals of Oncology, are added to other investigations already carried out on this same blood test for the early diagnosis of tumors. The new analysis included 2,823 patients with a diagnosis of cancer and 1,254 healthy people: all underwent a test for the analysis of methylation profiles of free circulating DNA (cell-free DNA, cfDNA, which originated from tumors and non-tumors) and the molecular analyzes performed in liquid biopsy were then coupled to a prediction algorithm based on artificial intelligence. The system of machine-learning developed in the study, appropriately “trained” and “fed” with information relating to the methylation profiles of cfDNA, not only proved capable of distinguishing patients with cancer from healthy ones, but also provided important information on the tissue of origin and on the possible localization of the primary tumor – he explains Antonio Russo, professor of Medical Oncology at the University of Palermo and member of the board of directors of the Italian Association of Medical Oncology (Aiom) -. Thanks to the help of artificial intelligence the test proved capable of detecting more than 50 different types of tumors with a false positive rate, that is, subjects positive for the new diagnostic test but not suffering from cancer of 0.5%. And with a sensitivity, that is, the percentage of subjects diagnosed with cancer and positive to the test, which varies according to the stage of the disease. In fact, a sensitivity of about 17% was recorded for stage I tumors, 40% for stage II, 77% for stage III, while for stage IV tumors the sensitivity was close to 90%. These figures are extremely encouraging if we think that the performance remains at high levels even for poor prognosis tumors such as pancreas, bladder, intestine, stomach, anus, liver, biliary tract and others that are generally diagnosed at an advanced stage and for which a screening test is not currently available.
What is the test for today
Ultimately the study demonstrates a good performance of the test, which, however, is still too influenced by the stage of the disease. In practice, to date, the examination is able to detect in 9 cases out of 10 already metastatic neoplasms (stage IV), but not very accurate in the early stages. If the sensitivity in stage I is less than 20% it means that 8 times out of 10 we tell someone that they do not have cancer while they have it and this will lead them to feel calm and underestimate any signs or symptoms. Giordano Beretta, Aiom national president -. a very interesting research, but still very far from clinical practice: i.e. these results are not, for now, useful in order to provide a tool to be used like one of the screening tests currently used (e.g. mammography) and therefore applicable to the entire healthy population to intercept tumors at an early stage . Suffice it to consider that liquid biopsy is not yet a standard for those who already have cancer, let alone on healthy subjects. On the other hand – continues Beretta – the main strength of the study is its high specificity (99.5%), that is the test results in a very low percentage of false positives, equal to 0.5%. If not yet sufficiently effective for early diagnosis in healthy people, what other possible applications could the test have? It could contribute to significantly change our daily clinical practice in a short time – concludes Russo -. I am referring for example to the possibility of diagnosing so-called “natural to be determined” neoplasms, for which the histological examination is not conclusive. Or, in the post-surgical disease phase with radical intent and healing objective, with the aim of intercepting the presence of disease residues found in the blood and which could indicate the subjects most at risk of relapse to therefore be candidates for precautionary chemotherapy treatment (adjuvant ).
August 1, 2021 (change August 1, 2021 | 12:43)
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