The study data – presented at the 11th Annual AACR International Conference on Frontiers in Cancer Prevention Research, USA, - suggests that the two red meat components could combine to form N-nitroso compounds, which in turn may increase risk for bladder cancer.
Additionally, the US-based researchers said people who have reduced ability to reverse the effects of N-nitroso compounds because of a genetic variation in a specific gene (known as RAD52) could be at particularly high risk.
"Nitrosamine formation occurs predominantly in the stomach and intestines, so these exposures have been studied extensively in relation to gastric cancer and somewhat in relation to colorectal cancer," said Chelsea Catsburg from the University of Southern California, USA – who led the research.
Catsburg and her colleagues had previously found that meat groups with high heme and high amine concentrations – such as salami and liver – increased risk for bladder cancer. In this study, they examined whether genetic variation in DNA repair enzymes, available to correct the damage caused by these endogenously formed carcinogens, modified these associations.
The researchers collected data from 355 bladder cancer cases and 409 controls in the Los Angeles Bladder Cancer Study.
"We found that a polymorphism in the RAD52 gene modified the effect of these exposures," Catsburg said.
"This polymorphism is suspected to reduce the DNA repair activity of the RAD52 protein, and the association of these meat groups and bladder cancer risk was significantly higher in individuals with one or more copies of this polymorphism."
Such findings further support recommendations by the World Cancer Research Fund to limit red meat intake and to avoid processed meats to reduce risk for stomach and bowel cancer, the researchers added.
"This study suggests that these exposures may also affect secondary organs such as the bladder," Catsburg said.
"Individuals at risk for bladder cancer may wish to avoid intake of red and processed meats, especially if they have genetic polymorphisms that reduce DNA repair activity and make them more vulnerable to the effects of carcinogens."
Further replication of this study to support an association between heme and meat intake and the risk for bladder cancer is necessary, she added.