Organized lung cancer screening: arriving in small steps

Lung cancers are the leading cause of cancer mortality in France, responsible for more than 33,000 deaths each year. In 80% of cases, they are attributable to tobacco. Most often detected at an advanced or metastatic stage, a stage at which curative treatment is no longer possible, they have a poor prognosis. One of the major challenges is therefore to diagnose the disease at a localized stage.

Efficiency is no longer up for debate

“For more than thirteen years now, we have had strong scientific arguments demonstrating that a screening strategy, using low-dose chest CT, reduces mortality from bronchopulmonary cancer and overall mortality in an at-risk population,” recalls Dr Olivier Leleu (Abbeville). Two large studies, NLST and Nelson, demonstrated a significant reduction in lung cancer mortality, of around 20%. The Italian Mild study also showed a reduction in mortality, from 39% to ten years, with annual or biannual screening for more than five ans. “More recently, a Cochrane meta-analysis (1) confirms, on more than 100,000 participants, a significant reduction in lung cancer mortality, of 21%, and in overall mortality of 5%,” adds the specialist.

The scientific obstacles therefore no longer exist and we are moving towards organized screening in France. It is already implemented in other European countries (Croatia, Czech Republic, Poland). “England also launched a program at the beginning of 2023. More than 2 million invitations were sent, 5,000 cancers were detected, 76% of which were at a localized stage. Note that organized English screening has certain particularities: mobile screening with an on-board scanner, lung cancer risk prediction models with, in addition to smoking and age, criteria such as level of education, history family history, history of respiratory diseases, says Dr Leleu.

A pilot program tested soon

“This year, a notable step forward was made, with the launch by the Inca, in mid-July, of the call for projects for the establishment of a national pilot screening program. A research project file involving humans (Riph 2 type) has been submitted, and the response is expected soon. This clinical trial will make it possible to define the criteria for a screening program at the national level and to evaluate the most effective modalities for the target population. It will have to answer the questions remaining unanswered before a possible generalization, within five to ten years, explains Dr. Leleu. We are making progress… but it is still a long way, because it is a research program that is difficult to implement. »

The target population is people aged 50 to 75, active smokers (or who have quit for less than fifteen years), more than 20 pack-years or more than 10 cigarettes per day for more than thirty years, or more than 15 cigarettes per day for more than twenty-five years. Screening uses low-dose CT, repeated one year later, then every two years (if both are negative). Participation in the pilot program must systematically be accompanied by a proposal for smoking cessation support and may be associated with spirometry. The scanner should also make it possible to look at the state of the coronaries, emphysema and osteoporosis.

A real-life assessment

At the same time, numerous studies are being carried out, notably DEP-KP80, which evaluated in real conditions the feasibility of screening for lung cancer using low-dose chest CT in the Somme department. The final results have just been published in the Lancet (2). 1,254 high-risk people, aged 55 to 74, active or quit smokers with at least 30 pack-years of smoking, were recruited.

Three chest CT scans were performed one year apart. Participation in each of them amounted to 75.4% for the first, 42.8% for the second and 31% for the last.

42 cancers were diagnosed, of which 71.4% were at stage 1 or 2 and 34 cancers (80.9%) were treated surgically. These results underline the effectiveness of the technique and its feasibility. They also highlight the need to optimize participation in screening. “It appears that active smokers and younger people (under 65) participate less in screening; this is also the case for the most precarious populations. Hence the notion of “go towards”with a traveling truck, equipped with a scanner, for example”, suggests Dr Leleu, who coordinates this study.

(1) A. Bonney et al. Cochrane Database Syst Rev. 2022 Aug 3;8(8):CD013829
(2) EBioMedicine. 2024 Nov:109:105396