Conclusions

This atlas shows major variations, sometimes more than two-fold, in the risk of several cancers, across the island. For many cancers, we found a strong relationship between markers of socio-economic status and cancer risk, sometimes positive, sometimes negative. These socio-economic relationships were more consistent than the broad geographical patterns identified by mapping. Few of the geographical patterns could be satisfactorily explained by the available data on risk factors, although we did see some correlations between smoking prevalence and smoking-related cancers.

Some differences in relative risk appeared to be attributable to health service provision—higher levels of breast screening in NI in the 1990s; more prostate specific antigen testing in RoI. For a few cancers, the more demand-led service in RoI may lead to more case-finding and an apparently higher overall cancer risk, as seen in its most extreme form for prostate cancer.

We were struck by the relative paucity of comparable information on established cancer risk factors at individual, small area or national level in both countries. Sources of data are fragmented and often either unavailable or not published. Understanding the reasons for geographical variation, and taking appropriate action, would reduce the cancer burden significantly in Ireland. We hope that this atlas will serve as a stimulus and raw material for detailed studies which will explore and answer some of the questions it poses.