Epidemiological impact of lung cancer screening by low dose CT scan in the French Department of the SOMME.

Context: Lung cancer is the leading cause of cancer death worldwide. In recent years, screening using low-dose CT scan has shown a reduction in lung cancer-related mortality and in all-cause mortality. The DEP KP80 study was implemented in the French department of the Somme with the aim of investigating lung cancer screening in practice. The results of the first round showed a prevalence of 2.7% for lung cancer, with the majority at localized stages (77%). The primary objective of our study was to compare the stage at diagnosis of patients with lung cancer screened as part of DEP KP80 and those who were not screened. The secondary objectives were to describe the epidemiological characteristics of lung cancer in the French department of the Somme for the period in question and to compare survival rates in screened and unscreened patients.

Methods: This retrospective cohort study compared from May 2016 to December 2017 the characteristics of patients with lung cancer screened as part of DEP KP80 and those who were not screened, using data from the Somme Cancer Registry.

Results: In total, 644 patients with lung cancer were included (18 in the screened group and 626 in the unscreened group). There was a significant inversion in the stage distribution at diagnosis, with a predominance of metastatic or locally advanced stages (69%) and a minority of early stages (31%) in unscreened patients, and a majority of early stages (77.8%) and a lower proportion of locally advanced or disseminated stages (22.2%) in screened patients (p < 0.01). In the screened group, there was a significant improvement in survival, a higher rate of surgical resection, and a longer time interval between first contact and treatment initiation.

Conclusion: Lung cancer screening by low-dose CT scan in the French department of the Somme showed an impact on stage at diagnosis, with a majority of early stages in screened patients, allowing for curative treatment with a significant improvement in survival.