To avoid dying of lung cancer, the easiest way is still not to smoke. But beyond this evidence, scientists have shown for more than ten years now that scanners offered at regular intervals to smokers or former smokers make it possible to very significantly reduce the mortality linked to these tumours, which cause more than 33,000 deaths per year in France. Since then, all over the world, pulmonologists and oncologists have been campaigning in favor of this screening. The United States, China, South Korea and the Netherlands have already implemented it. In the United Kingdom, the leaders of the NHS, the national health system, even finance buses equipped with scanners, which are parked in supermarket car parks to allow as many people as possible to carry out these examinations.
And in France? The ten-year strategy for the fight against cancer launched on February 4, 2021 by the President of the Republic, has placed this subject among its priorities. But in practice, thinking is progressing slowly. The stakes, however, are high. These scanners make it possible to identify tumors at an early stage, when they are still operable and have not led to the appearance of metastases. “The lungs are not innervated, and a lesion can reach up to 4 or 5 centimeters before starting to cause symptoms. Today, most patients are therefore diagnosed very late, when the disease is already too advanced to hope to cure them”, regrets Professor Nicolas Girard, coordinator of the Curie-Montsouris Thorax Institute.
A cancer that can be cured if it is taken care of very early
Despite its reputation as a killer, lung cancer can indeed be successfully treated if caught early. Oncologists are used to saying that, schematically, the five-year survival rate decreases by 10% each time the tumor gains one centimeter. Thus, it is 90% for a lesion of one centimeter, but drops to 50% when it reaches five. “Two large studies, one American, the other European, have shown that screening can reduce mortality by 20% to 35%, continues Professor Girard. That is, applied to France, from 7,000 to 12,000 lives saved per year”. Not to mention that these examinations can also sometimes reveal other tobacco-related pathologies, such as coronary heart disease, for example.
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In 2016, however, the High Authority for Health had vetoed this screening. “This blocked any possibility of moving forward, because in our country, this type of program can only be set up if this body validates the interest. We could not even carry out experiments”, regrets Professor Girard. In question, a lack of conclusive data, according to Dr Lise Alter, director of medical, economic and public health assessment at HAS: “At that time, only one trial published by an American team suggested that a Screening by low-dose CT scan could reduce specific mortality, but the conditions for carrying out this study were not representative of the French context. Elements were also against screening (high frequency of false positives, increased risk of complications). For us, the level of proof was therefore not sufficient. Since then, we have continued the analysis of the literature, in particular with meta-analyses with a high level of proof, which have enabled us to update our work and issue new recommendations.”
Indeed, HAS experts opened the door to screening at the beginning of the year – four years after the publication of a major European study, which once again demonstrated the benefit of this screening. And again, this is not a positive opinion, but the possibility of launching a pilot program. Why such caution? “We want to move forward, assures Lise Alter, but we do not yet have all the answers to our questions. Many points remain to be clarified before we can move towards a program on a national scale”.
At the top of the list, the delicate question of “false positives”, when imaging shows a lesion which ultimately turns out to be benign. “When we scan smokers or former smokers, we find nodules in 30% of them, but they are only tumors in 1% of cases,” admits Nicolas Girard. The debates around overdiagnosis and overtreatment, already virulent with regard to breast cancer screening, could take on a new dimension here. A biopsy can indeed make it possible to decide, but it is unthinkable to offer this invasive and potentially risky procedure to all patients in whom a CT scan would have shown an anomaly. “The scanners must be read by experienced teams, who will be able to decide on the best course of action to take”, answers Professor Girard. Most often, faced with a lesion of less than one centimeter, it will suffice to repeat the scanner after a few weeks to monitor the evolution, assures the specialist.
Smokers or ex-smokers over 50 more concerned
There is therefore also a stake in the organization of care, because it will be necessary to ensure that the experts will be available and in sufficient numbers. Depending on the criteria used, the target population could quickly turn out to be large. Oncologists believe that smokers or ex-smokers over the age of 50, who have more than 25 years of smoking and who, if necessary, have been weaned for less than 15 years, could be concerned. “This is a point that still needs to be validated, nuance Lise Alter. We are also wondering if we should include people exposed to passive smoking, or take into account the quantity of cigarettes smoked”.
Hence the importance of this pilot program for HAS. Especially since other points are still under discussion: the rate at which the scanners should be repeated, but also the dosimetry used, the territorial distribution of the devices used (low-dose scanners, which may not be available everywhere ), the training of professionals, the acceptability in the population, or even the impact on smoking. Some are worried about the risk of falsely reassuring smokers, who would then be less encouraged to quit. It will also be necessary to find how to contact the people concerned, since the main criterion, smoking, does not appear in any public database…
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It is up to the National Cancer Institute (Inca) to organize the program which will have to answer all these questions. But it looks long. The Inca is at the start of the process: it goes through the establishment of a working group, which will have to determine the specifications, the start date, or even the number of people who can be included, on the basis of ongoing clinical studies in a few expert centers. The pilot program should therefore only start in 2023, with the idea of achieving generalization within five years. How many preventable deaths in the meantime?
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Christian Gollier’s Time.news
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