Incidence of solitary pulmonary nodules in Northeastern France: a population-based study in five regions

The discovery of a solitary pulmonary nodule (SPN) on a chest imaging exam is of major clinical concern. However, the incidence rates of SPNs in a general population have not been estimated. The objective of this study was to provide incidence estimates of SPNs in a general population in 5 northeastern regions of France.

This population-based study was undertaken in 5 regions of northeastern France in May 2002-March 2003 and May 2004-June 2005. SPNs were identified by chest CT reports collected from all radiology centres in the study area by trained readers using a standardised procedure. All reports for patients at least 18 years old, without a previous history of cancer and showing an SPN between 1 and 3 cm, were included.

A total of 11,705 and 20,075 chest CT reports were collected for the 2002-2003 and 2004-2005 periods, respectively. Among them, 154 and 297 reports showing a SPN were included, respectively for each period. The age-standardised incidence rate (IR) was 10.2 per 100,000 person-years (95% confidence interval 8.5-11.9) for 2002-2003 and 12.6 (11.0-14.2) for 2004-2005. From 2002 to 2005, the age-standardised IR evolved for men from 16.4 (13.2-19.6) to 17.7 (15.0-20.4) and for women from 4.9 (3.2-6.6) to 8.2 (6.4-10.0). In multivariate Poisson regression analysis, gender, age, region and period were significantly associated with incidence variation.

This study provides reference incidence rates of SPN in France. Incidence was higher for men than women, increased with age for both gender and with time for women. Trends in smoking prevalence and improvement in radiological equipment may be related to incidence variations.