Using 2008 global cancer rates from the World Health Organization, a new international study has found that certain lifestyle factors - specifically smoking and eating diets high in animal products - have the strongest association with cancer rates.
Publishing their findings in the journal Nutrients, the researchers say the results could impact international food policies.
The investigators looked at cancer rates for 21 different cancers from 157 different countries in 2008 and statistically compared these rates with indices for risk-modifying factors.
The Food and Agriculture Organization of the United Nations provided dietary supply data dating back to 1980. According to the researchers, there is usually a lag of about 20 years between dietary changes and peak cancer rates.
Meat, fish and eggs were included in the animal products index, and lung cancer rates were used as an index for smoking and air pollution effects.
Over half of the cancer incidence rates were explained by smoking and animal product indices among the 87 countries, the study shows.
Additionally, alcoholic beverage supply explained a smaller, yet still significant amount of the cancer rates.
'Lesson for national food policies'
The data showed that diets high in animal products had the strongest association to rates of certain cancers, including breast and prostate.
The smoking index was twice as important as the animal product for males, the team notes.
However, for females, the animal product index was twice as important, uncovering a gender difference in risk factors.
The team found that animal products had the strongest correlation among certain cancers, including female breast, kidney, ovarian, pancreatic, prostate, testicular and thyroid cancer.
Animal products may increase cancer risks, the researchers say, because they promote growth of the body as well as tumors by producing insulin-like growth factor-I (IGF-I).
They use the Japanese population as an example, noting that older Japanese generations are generally shorter than Westerners, while younger generations are about as tall.
Although the traditional Japanese diet received only 10% of its calories from animal products, Japan has since transitioned to a more Western diet, in which 20% of the calories come from animal products.
The team also notes that rates of cancers common in Western countries have increased significantly in Japan over the past 20-30 years.
Dr. Neal Barnard, president of the Physicians Committee and a faculty member of the George Washington University School of Medicine, says:
"This is an important study showing strong relationships between meaty diets and cancer risk. There's a clear-cut lesson there for national food policies."
Other findings from the study reveal that alcoholic beverage supply correlated with colorectal cancer, and added sweeteners were linked to incidence of brain cancer in females, pancreatic and prostate cancer.
Medical News Today recently reported on a study that suggested eating a tomato-rich diet may reduce the risk of breast cancer.