Improved survival from lung cancer in British Columbia compared to Scotland—Are different treatment rates the whole story?

To explore possible causes of the poor survival of Scottish lung cancer patients, a retrospective registry-based audit was conducted comparing demography, treatment and survival of 3833 Scottish patients and 2073 from British Columbia (BC). Patients from Scotland were older, had a lower rate of pathological confirmation (74% vs 89%, p < 0.001), but more squamous (51% vs 31%, p < 0.001) or small cell (SCLC) (18% vs 15%, p = 0.005) cancers. Fewer Scottish patients received any treatment (57% vs 66%, p < 0.001) or treatment aimed at cure (14% vs 26%, p < 0.001). Survival was lower in Scotland (median 3.6 months vs 7.3 months; 5% vs 10% 5-year overall survival, p < 0.001), irrespective of treatment intent (potentially curative treatment median survival 20.9 months vs 34.0 months, 5-year overall survival 29% vs 34%, p < 0.001; palliative treatment 5.0 months vs 6.3 months (p < 0.001) and no treatment 1.4 months vs 2.5 months (p < 0.001)). With treatment intent included in a multivariate analysis, the hazard ratio for death for lung cancer patients in Scotland compared to British Columbia was 1.5. Relative survival was higher in BC (38% at 1 year and 12% at 5 years vs 22% and 6%, p < 0.001), indicating that life expectancy differences between the two countries was not the explanation. Reduced levels of treatment could only partially explain survival differences and other unknown factors related to lifestyle differences such as diet and smoking, co-morbid diseases, population genetics or cancer biology, may be important and warrant further exploration.