The suspected role of cow's milk, cheese, and other dairy products in hormone-dependent cancers

... One study compared diet and cancer rates in 42 counties. It showed that milk and cheese consumption are strongly correlated to the incidence of testicular cancer among men ages 20 to 39. Rates were highest in places like Switzerland and Denmark, where cheese is a national food, and lowest in Algeria and other countries where dairy is not so widely consumed.

Cancer rates linked to dairy can change quickly, said Ganmaa. In the past 50 years in Japan, she said, rising rates of dairy consumption are linked with rising death rates from prostate cancer - from near zero per 100,000 five decades ago to 7 per 100,000 today.

Butter, meat, eggs, milk, and cheese are implicated in higher rates of hormone-dependent cancers in general, she said. Breast cancer has been linked particularly to consumption of milk and cheese.

In another study, rats fed milk show a higher incidence of cancer and develop a higher number of tumors than those who drank water, said Ganmaa. ...

More: http://www.news.harvard.edu/gazette/2006/12.07/11-dairy.html