Caused by the transformation of cells that become abnormal and proliferate excessively, cancer is a scourge as old as life. But progress in research has made it possible to better understand this disease, the cause of nearly 10 million deaths a year worldwide: we now know that for the same organ, there is not “one” but “some” cancers. And that for the same type of cancer, there can be different tumors.
“Talking regarding colon cancer or breast cancer means nothing; the challenge today is to define what cancer looks like biologically,” explains doctor Fabrice André, director of research at the Gustave-Roussy cancer center.
For example, there are three main types of breast cancer, which are not receptive to the same treatments. In recent years, “the development of molecular technologies has made it possible to better identify which abnormal proteins to block” for each type of tumour, continues Prof. André.
This better understanding of the disease led to the emergence in the 2000s of targeted therapies, targeting a specific genetic mutation.
Immunotherapy, an important progress
Previously, chemotherapy was often the only treatment offered: however, by aiming to eliminate cancer cells, regardless of their location in the human body, it might cause side effects.
For several types of cancer, such as certain forms of leukemia, “targeted therapies have been a revolution”, underlines Professor Bruno Quesnel, director of research and innovation at the French National Cancer Institute (INCA).
Over the past ten years, immunotherapy has emerged as the most important progress in oncology. The principle: the patient becomes his own medicine. Unlike chemotherapy, we no longer target the cancer cells themselves but the immune cells that surround them in order to activate them. Reboosted, it is the latter that destroy the tumor cells. This discovery won the 2018 Nobel Prize in Physiology and Medicine for James Allison of the University of Texas and Tasuku Honjo of Kyoto University.
For some cancers, this discovery was major. For example, before 2010, the survival rate for patients with metastatic melanoma (the most serious skin cancer) was very low. Thanks to immunotherapy, life expectancy has increased by up to ten years, compared to a few months previously.
But not all tumors respond to this treatment, which can also cause side effects.
Artificial intelligence, better define the prognosis
“We are only at the beginning of immunotherapy”, assures Professor Bruno Quesnel. The variations of this new therapeutic weapon are already numerous: bispecific antibodies, cell and gene therapies (CAR-T cell)…
“We will now have to succeed in combining the treatments as intelligently as possible, notes Pierre Saintigny, oncologist at the Léon Bérard center in Lyon. With immunotherapy, we have climbed a stage in the treatment of cancer, but there are still steps to climb for all the patients who do not benefit from it. »
Researchers can rely on the ability of biotechnologies to develop new drugs that are ever more specific and less toxic.
Another pillar on which to rely: the development of artificial intelligence (AI), which already allows a better definition of the prognosis of cancer. Thanks to her, “we will be able to identify which patients can benefit from a short treatment”, assures Fabrice André. Advantage: therapeutic de-escalation for patients and lower costs for the community.
Breast cancer pioneered the use of AI, which should now benefit other cancers.
Another hope lies in the ability to detect a tumor very early in the body. “We already do this in the United States by looking at DNA through a simple blood test, but there are still a lot of false positives,” notes Fabrice André.
Before the generalization of such a technique, prevention remains to this day the best way to avoid a large part of cancers.
Isabelle TOURNÉ/AFP
Soon a simple blood test to identify or monitor the disease?
Dozens of studies are underway to demonstrate the usefulness of a new tool in monitoring patients treated for cancer, the “liquid biopsy”. This technique is nothing other than a blood test which aims to find DNA fragments from the tumor or cancer cells. It has considerable advantages: in particular, it is much less invasive than a “classic” biopsy, which takes tissues from the body. Above all, it contains very precise information on a patient’s cancer. “The sampling of what is called “circulating DNA” aims to detect mutations, for certain types of cancer, and thus adapt treatments accordingly”, explains Alain Thierry, research director at the Research Institute in oncology in Montpellier (south of France).
For certain cancers such as those of the lung, where the tumors are often difficult to access, this is a real breakthrough. The blood test might also soon make it possible to monitor how a cancer reacts to treatments. “In concrete terms, following the surgical removal of a tumour, chemotherapy is often prescribed when we do not know if the patient really needs it,” notes Mr. Thierry.
In the future, the analysis of a patient’s blood may, in many cases, make it possible to administer lighter or shorter treatments, but also to detect possible recurrences.
But the liquid biopsy also conceals other potentials, certainly much more uncertain: the early detection of cancer. Several teams and biotechs are working on it around the world. The idea: to be able to detect a tumor in an individual by taking a blood sample, even before symptoms appear or it is visible on an X-ray.
“Technologically, it is much more complicated than cancer monitoring because it requires large-scale analysis of DNA mutations but also other specific markers, while not knowing in advance what we are looking for”, describes François-Clément Bidard, oncologist at the Institut Curie in Paris.
Recently, the results of a study by the American biotech Grail were particularly noticed: in the trial, a blood test made it possible to detect cancers in individuals aged 50 and over who were a priori healthy. More than 6,600 people took the test. There was a suspicion of cancer for 92 of them. In the end, 35 actually had confirmed cancer during the year and 57 people therefore mistakenly believed that they had one. But the test made it possible to detect 9 cancers which would probably not have been detected by early conventional screening.
However, the results are very mixed and it will probably take years to improve the reliability of these tests, which are already marketed in the United States. And, even reliable, these tests will still raise certain questions, warns François-Clément Bidard. “One of them is the cost, this type of sequencing being extremely expensive. Another subject is the possible “overdiagnosis” induced by these tests, because a certain number of cancers detected have in fact an extremely slow evolution and do not necessarily call for treatment”, he explains.
Caused by the transformation of cells that become abnormal and proliferate excessively, cancer is a scourge as old as life. But progress in research has made it possible to better understand this disease, the cause of nearly 10 million deaths a year worldwide: we now know that for the same organ, there is not “one” but…
