Lung Cancer Screening With Low-Dose Computed Tomography Beyond the National Lung Screening Trial
Menée aux Etats-Unis sur une cohorte incluant 32 640 fumeurs ou anciens fumeurs (âge : 55 à 74 ans), cette étude évalue, par rapport aux participants pouvant bénéficier d'un programme de dépistage du cancer du poumon par radiographie à faible dose de rayonnements, le risque de cancer du poumon chez les participants non éligibles au programme et consommant entre 20 et 29 paquets de cigarettes par an, puis analyse leurs caractéristiques démographiques
Low-dose computed tomography (LDCT) allowed the National Lung Screening Trial (NLST) to identify a 20% decrease in lung cancer–specific mortality that had eluded earlier investigators of chest radiography using randomized trials and case-controlled studies of LDCT that were not designed to detect mortality effect (1–3). The NLST was designed with 90% power to detect a 20% reduction in mortality between LDCT and chest x-ray (CXR) (4). CT scans are expensive as a screening test, although not as expensive as colonoscopy. Limiting LDCT to three annual rounds still required over 150, 000 LDCT scans. Selection of individuals at very high risk for the development of lung cancer during the follow-up period of the study was paramount, leading NLST to focus on smokers with 30 or more pack-years. Prior randomized trials of CXR and single-arm LDCT also informed the design.
The Mayo Lung Project (MLP) randomly assigned over 9000 male smokers over the age of 45 years between 1971 and 1983 (1). Participants were randomly assigned to CXR and sputum cytology every four to six months for six years or “usual care” without recommendation or restriction. This difference between the two groups of participants decreased as the control group received CXR screening as “usual care.” Even with the extension of median follow-up to more than 20 years, the MLP failed to find a lung cancer–specific mortality difference between the arms despite improved survival in the intervention arm (1). Overdiagnosis in the intervention arm may have contributed to an improved survival advantage. Undefined “usual care” led to a decreased difference between the intervention and control arms.
The introduction of helical or spiral CT scanning technology in 1989 provided cross-sectional images of lungs during a single breath-hold. This technology was explored in the Early Lung Cancer Action Program (ELCAP) and in Japan, where lepidic …
Journal of the National Cancer Institute , éditorial, 2015