Czech Study on Lung Cancer Screening: post-trial follow-up of lung cancer deaths up to year 15 since enrollment
Abstrakt
BACKGROUND. The study was launched in the mid-1970s to explore the capability of screening by chest X-ray and sputum cytology to be used as an effective component of the lung cancer control program in the Czech Republic, a Central European country with a high and increasing occurrence of lung cancer in men at that time.
A complementary objective of this report is to ascertain whether the cumulative numbers of lung cancer deaths would equalize in the two randomized groups during a prolonged follow-up period. METHODS.
Six thousand three hundred sixty-four males who were heavy cigarette smokers, aged 40-64 years, were enrolled during a general health survey in 6 districts of the Czech Republic. At initial X-ray and sputum examination, 19 prevalent lung carcinoma cases were diagnosed.
After stratified randomization, the remaining subjects entered a 3-year study: the intervention group (3171 participants) was subjected to semiannual chest X-rays and sputum investigation whereas the controls (3174 participants) had 1 examination only by chest X-rays and sputum investigation, 3 years after entry. During a further 3-year follow-up, a chest X-ray was taken at the end of Years 4, 5, and 6 for both the intervention and control groups.
Subjects in both groups who were suspected to have lung carcinoma or other disease on the basis of screening results or symptoms were subjected to appropriate diagnostic studies and treatment. Data on all causes of death in Years 1-6 and on deaths from the lung cancer in Years 7-15 of participants in the intervention and control groups were compared.
RESULTS. The incidence rate of lung carcinoma from the intervention group was significantly higher than from the controls in the initial 3-year study period (P < 0.05), but not for the initial 6-year period (P = 0.06).
Lung carcinoma cases detected by screening were identified at an earlier stage, were more often resectable, and had a significantly better survival than interval cases diagnosed mainly because of symptoms. There was no significant difference in the lung cancer mortality rate between the 2 groups in the initial 3-year study period or during follow-up prolonged up to Year 15 since enrollment.
CONCLUSIONS. The study gave no evidence that screening for lung cancer by chest X-ray is beneficial in terms of reducing mortality.
Based on the results of this study, there is no justification to recommend semiannual screening as a component of a comprehensive lung cancer control program.