Scientists identify new prostate cancer risk: IGF-1

Greater levels of a protein called Insulin-like Growth Factor-1 (IGF-1)* results in increased risk of prostate cancer, according to a study published in the Annals of Internal Medicine today.

An international team of researchers, led by the University of Oxford, collected and analysed data from 12 previous independent studies on the relationship between blood concentrations of suspected prostate cancer risk factors, and subsequent onset of the disease. Previously, some but not all studies have suggested a link between IGF-1 levels and increased risk of developing the disease.

IGF-I levels are influenced by lifestyle factors such as diet, so the results of this rigorous analysis could help scientists find ways to reduce men’s risk of developing prostate cancer by tailoring advice to men at high risk.

The scientists looked at the data of blood samples of 3,700 men with prostate cancer and 5,200 men without the disease. Blood samples were taken on average when the men were 62 years of age, five years before they were diagnosed with prostate cancer. The research found that men with higher levels of IGF-1 were more likely to go on to develop prostate cancer than those with lower levels of the protein.

Lead author Dr Andrew Roddam, a Cancer Research UK epidemiologist at the University of Oxford, said: “There is a need to identify risk factors for prostate cancer, especially those which can be targeted by therapy and/or lifestyle changes. Now we know this factor is associated with the disease we can start to examine how diet and lifestyle factors can affect its levels and whether changes could reduce a man’s risk.

“But it’s important to point out that there is no evidence to suggest that measurement of IGF-1 levels could be used to develop new prostate screening methods. Other studies have shown that existing methods of detecting prostate cancer are not improved by also measuring IGF levels.”

Prostate cancer is the most common cancer in men in the UK accounting for a quarter of all new cases of cancer diagnosed in men. More than 34,000 men in the UK are diagnosed with prostate cancer each year. The disease is the second most common cause of cancer death in UK men, after lung cancer and causes around 10,000 deaths a year. 

Dr Lesley Walker, Cancer Research UK’s director of cancer information, said:  “While there are established risk factors associated with prostate cancer of age, family history and ethnicity there are no clear data on modifiable risk factors. Research like this is vital to further the work on prevention and treatment of the disease. The findings are also likely to be of interest to scientists who are looking at developing drugs to prevent prostate cancer.

*IGF-1 and relevance to all cancers

Other studies have investigated the connection between circulating IGF-I levels and the development of other common cancers. Although there is some evidence that IGF-1 levels may be related to an increased risk of breast cancer, results from individual studies are somewhat conflicting. There is also some evidence that IGF-I may be linked with colorectal cancer, but the data is more sparse than for breast cancer. For other cancers the data is limited.