Overweight and obesity are directly responsible for around 800 new cases of cancer every year in Ireland, and 300 cancer deaths, a new study has shown.

According to researchers from the Department of Public Health and the HSE's National Cancer Control Programme, an estimated 43% of cancers are related to exposure to 14 lifestyle and environmental factors, such as smoking and alcohol consumption. However, people are less aware of the role of excess body weight in the development of cancer.

They decided to look into this further by calculating the proportion of cancers in Ireland that were attributable to overweight and obesity, using a method known as the population attributable fraction (PAF). This fraction was then applied to incidence and mortality data for specific cancers diagnosed in Ireland between 2003 and 2012.

This allowed the researchers to estimate the number of new cases of cancers and cancer deaths that were caused by excess body weight during this period.

"We found that each year in Ireland, approximately 800 new cancers and 300 cancer deaths are attributable to excess body weight. This is a major cause of cancer, responsible for 4.5% of all cancers in Ireland. Public awareness of this significant preventable risk must improve," they said.

Over the 10-year period (2003-2012), a total of 3,682 newly diagnosed male cancers and 4,157 newly diagnosed female cancers were attributable to excess body weight.

Meanwhile, 1,602 male cancer deaths and 1,501 female cancer deaths were also attributable to excess body weight during this period.

Overweight and obesity were linked to a number of different types of cancer, including colorectal, breast, oesophageal, endometrial and renal.

"Excess body weight is one of the most important causes of cancer. However it is likely the public are more aware of the risks associated between excess body weight and diabetes or heart disease, than the risk of cancer.

"A clear and concerted information campaign for both healthcare professionals and the public is needed to highlight the risk of excess body weight and cancer. Further initiatives must be taken to counteract obesogenic environments and facilitate necessary behaviour change," the researchers concluded.

Details of these findings are published in the Irish Medical Journal.