Temporal trends and spatial variation in stage distribution of non-small cell lung cancer in the Netherlands

Introduction To explore regional and temporal variation in clinical stage distribution of non-small cell lung cancer (NSCLC) and link the observations to the introduction of positron emission tomography (PET). Method All NSCLC patients diagnosed between 1989 and 2007 were selected from the Netherlands Cancer Registry (n=126,962). Maps of smoothed percentage distribution of clinical stage NSCLC were conducted by period of diagnosis. Join point regression analyses were performed to detect trends over time. Geographic variation in stage distribution was evaluated using spatial scan statistic. To evaluate the impact of PET in regions proportions of stage IV and Estimated Annual Percentage of Change (EAPC) were calculated for two regions in which PET was introduced between 1995 and 2000 and for two regions without a PET scanner during this period. Results The percentage of stage I and unknown decreased with 7.4% and 13.3% between 1989 and 2007, while the percentage of stage IV increased with 23.4%. The most rapid increase in stage I and IV were observed between 1997 and 2003. In two regions with a PET scan the proportion of stage IV increased annually with 10.3 and 8.5% compared to 5.4 and 6.4% in two regions without a PET scan. Conclusion The most rapid changes towards more stage IV NSCLC diagnoses correspond with the implementation of PET. However, trends were already visible before PET was introduced and regions without PET also showed considerable increases in stage IV diagnose, suggesting other factors or improvements in diagnostics also contributed substantially.