Worryingly high rates of prostate cancer have been identified across the West of the country in a new map highlighting where the disease hits.
And rates of breast cancer, the second most common form of the disease in Ireland affecting more than 2,000 women every year, are higher in Dublin and Cork.
The new "health atlas" shows how people living in different counties are at higher risk of developing certain common cancers.
The "at-a-glance" differences have emerged in a new 26-county map compiled by the National Cancer Registry, which tracked cancer rates in counties between 1994 and 2012.
It highlights counties with higher than expected rates for different cancers that are not likely to have occurred by "random chance".
Men living in Galway, Mayo, Sligo, Roscommon, Cork and Wicklow have a greater chance of getting prostate cancer, the map reveals.
Lung cancer - which is mostly caused by smoking - is significantly higher in Louth, Carlow, Kildare and Dublin.
The risk of bowel cancer was high in Cork, with 268 cases observed annually against an expected rate of 241.
But in Dublin the annual incidence is 563, even though it should be 547 based on national averages.
The map raises new questions around why people in some counties are more prone to certain cancers than others.
Although lifestyle habits like smoking play a major role in some cancers, they do not reveal the full picture about other influences such as a person's genes.
Acting director of the registry, Dr Harry Comber, said the analysis adjusts for age and compares cancer rates in each county to overall national rates.
The most recent reports show that more than 122,000 people are living after cancer in Ireland and of these, 94,000 are still living 10 years after first being diagnosed.
Cancer incidence rates in Ireland remain high, with 2012 rates 10pc higher on average than those in Europe for men and 16p higher in women.
Dr Robert O'Connor, head of research at the Irish Cancer Society, said: "There are a number of factors that can go towards explaining the difference in cancer rates between counties. Population age, urban health behavioural patterns and socioeconomic differences are some of them.
"Socioeconomic circumstances are not associated with increased risk of prostate cancer, so age is more likely to be the major factor for higher prostate cancer incidence in some counties."
The rise in men getting PSA testing at their GP surgery to check for potential prostate cancer has also been cited as a reason for an increase in incidence.
Dr O'Connor pointed out: "Certain types of cancer are more common depending on your socioeconomic background, for example lung, stomach, mouth, head and neck.
"We know that at least one-third of cancers are caused by lifestyle factors, for example smoking, poor diet, high-calorie diet, obesity, high alcohol intake and lack of exercise.
"In lower socioeconomic areas, which can also primarily be urban areas, people might not be as aware of the risk factors for cancer and could be more likely to engage in higher risk lifestyles."
But Dr O'Connor said: "We need to invest in research into more effective ways of reducing the incidence of cancer and other illnesses across our population."
A spokeswoman for the HSE cancer control programme said screening services such as Breastcheck, which started in 2000, may be a factor in higher breast cancer incidence.
"We work with the Irish Cancer Society in improving the population's awareness of the symptoms and signs of cancer," she added.