The first all-Ireland cancer atlas has revealed unexplained variations in cancer risk depending on where you live on the island of Ireland.

The report shows that people living in the Republic generally have a higher risk of developing many cancers than people in the North. The cancers recorded were for the period 1995-2007.

Published by the the cancer registries in the Republic and Northern Ireland, it shows that people living in coastal and urban areas of the 32 counties have a much higher risk of skin cancer, and that lung cancer risk is higher in urban areas and in the east than in other areas.

The report also shows that men's risk of getting prostate cancer is much higher in the 26 counties than in the North, and your risk of getting lung cancer is highest if you live along a line running from Dublin to Donegal.

The report also shows that your risk of getting cancer increases depending on your economic status, and that there were some links between smoking prevalence and smoking-related cancers in some areas.

Lung, stomach, head/neck and cervical cancer risk was higher in areas of high unemployment or low educational achievement, while skin, breast and prostate cancer risk was lower in these areas.

The atlas also shows that cancer risk is higher in more densely populated areas and is higher for many cancers in areas with higher numbers of elderly people living alone.

The report says the relative risk of developing many cancers was higher in the Republic than in the North

"The risk of non-melanoma skin cancer, melanoma, leukaemia, bladder, pancreas and brain/central nervous system cancer was significantly higher for both sexes in RoI."

Some differences in relative risk appeared to be attributable to health service provision—higher levels of breast screening in Northern Ireland the 1990s; more prostate cancer testing by blood tests in the Republic, the report noted.

In Northern Ireland, the risk of lung cancer was higher for both sexes, as was the risk of non-Hodgkin’s lymphoma, head and neck cancers and cancer of the uterus for women.

The report suggests that while both jurisdictions collect cancer data in very similar and rigorous ways 'slight variations in how these cancers are reported by histopathologists, and how these reports are interpreted by registries, may lead to systematic differences in reported incidence rates.'

It added that while genetic factors might be responsible for a little of the geographical variations, genetic
variation was an improbable overall explanation for the patterns reported.

The report says looking at tobacco-related cancers, the geographical distribution of lung cancer clearly reflects the higher cigarette consumption in the east of the 26 counties, as does that for cervical cancer.

There was a markedly higher risk of leukaemia in the Republic than in Northern Ireland.

The report says this was 'a surprising finding given the low level of international variation in Europe and the paucity of modifiable risk factors, other than smoking.'

Some differences in relative cancer risk appeared to be attributable to health service provision—higher levels of breast screening in Northern Ireland the 1990s; more prostate cancer testing by blood tests in the Republic, the report noted.

The report recommends that areas with unexplained higher than average cancer risk should be studied in detail.

It says some of its findings  here are of major public health importance.

Firstly, the largely unexplained geographical patterns for some of the more common cancers - colorectal, melanoma and stomach cancer.

Also and the role of H pylori stomach bacteria, 'an-easily diagnosed and treatable risk factor', in the high rates of stomach cancer in the east and north-west.

The report also says action should be taken to reduce the prevalence of risk factors that people can do something about, such as tobacco, alcohol, overweight and UV exposure

It says campaigns and initiatives to help raise awareness of health lifestyle behaviours  among the public should emphasise the links between lifestyle and cancer.

Commenting on the findings, Dr Harry Comber of the Republic's National Cancer Registry said understanding the reasons for geographical variation in cancer risk, and taking appropriate action, would reduce the cancer burden significantly in Ireland.

"Areas with unexplained higher than average risk should be studied in detail and a comprehensive programme of research into already known determinants of cancer risk in Ireland is needed to inform cancer control."