Generalisability of the results of the Dutch-Belgian randomised controlled lung cancer CT screening trial (NELSON): does self-selection play a role?

The degree of self-selection in the Dutch-Belgian randomised controlled lung cancer screening trial (NELSON) was determined to assess the generalisability of the study results. 335,441 (mainly) men born in 1928-1953 received a questionnaire. Of the respondents (32%), eligible subjects were invited to participate (19%). Fifty-five percent gave informed consent and was randomised. Background characteristics were compared between male respondents on the first questionnaire (n = 92,802), eligible subjects among them (n = 18,570) and those randomised (n = 10,627) and Statistics Netherlands 2002-2005 (SN) (n = 5289) or GLOBE study-data (Dutch cohort) (n = 696). Initial respondents were less likely to be highly educated (OR(adj) = 0.84; 95% CI: 0.74-0.96) and comprised of significantly less current smokers (OR(adj) = 0.65; 95% CI: 0.61-0.69) compared to the general population. These current smokers smoked more heavily (OR(adj) = 1.23; 95% CI: 1.10-1.37), but for a shorter time-period (respondents: 31, SN: 42 years, p < 0.001). Age, general health, BMI, alcohol use and cancer prevalence were comparable. The randomised population was younger (Age 50-65) (randomised subjects: 85.3%, SN: 72% (p < 0.01)) comprised of more heavy current smokers (OR = 2.08; 95% CI: 1.75-2.44), that smoked for a shorter period of time (randomised subjects: 37, SN_selection: 42 years (p < 0.001)). Both the respondents (32%) of the first questionnaire as well as the randomised population of the NELSON trial appeared to differ slightly on smoking characteristics, but the differences were limited and probably balance each other. Results of the NELSON trial will be roughly applicable to the Dutch and probably other populations that fulfil our selection criteria.

[The beginning of the end of the lung cancer epidemic among Dutch women]. / Longkanker bij Nederlandse vrouwen: het einde in zicht.

OBJECTIVE: To describe and interpret recent changes in lung cancer mortality and incidence, and changes in smoking prevalence among young and middle-aged women in The Netherlands. DESIGN: Secondary data analysis. METHOD: Mortality data were collected from Statistics Netherlands (CBS; 1960-2006), data on the incidence were obtained from The Netherlands Cancer Registry (NCR; 1989-2003), and data on smoking prevalence were collected from the Dutch Foundation on Smoking and Health (STIVORO; 1988-2007). Mortality and incidence rates were calculated for four age groups (20-44, 45-49, 50-54 and 55-59 years). Changes in trends in mortality and smoking prevalence were examined using joinpoint regression and birth cohort analysis. RESULTS: Since the 1960s, lung cancer mortality and incidence has increased dramatically among women in The Netherlands. In the mid-1990s, lung cancer mortality and incidence rates in young women (aged < 50 years) surpassed those in men. Mortality rates in young women (aged 20-49 years) increased 4-6% annually. However, these rates started to stabilise since 1999. Among women born after 1950, mortality rates and smoking prevalence have decreased. CONCLUSION: An end to the lung cancer epidemic in women in The Netherlands is in sight. The first indications are the recent reduction in mortality and incidence among young women, particularly in women born after 1950. In the future, this reduction is expected to translate into a stabilisation or modest decrease in total lung cancer mortality and incidence.