Study links processed meat and cancers

In 2015, the World Health Organisation’s International Agency for Research on Cancer (IARC) classified processed meat as a carcinogen. Now a new meta-study from Italy has confirmed links between the consumption of large quantities of the stuff and, specifically, female hormone-related cancers.

The IARC report describes processed meat as including hot dogs, ham, bacon, sausage, and some deli meats. It refers to meat that has been treated in some way to preserve or flavour it. Processes include salting, curing, fermenting, and smoking.

A related article in the publication Medpage Today says the association of processed meat consumption with some cancers is often attributed to factors such as high fat content, salt, additives or preservatives such as nitrites and nitrates, steroid sex hormone levels in animals, and harmful chemicals produced by processing and cooking.

The latest study, published in the journal Nutrition, takes data from a network of Italian hospital-based case-control studies conducted between 1982 and 2006. They include 5981 cases of breast cancer, 992 of endometrial cancer, 2002 of ovarian cancer, 1582 of prostate cancer, and a total of 16,394 control subjects with various non-cancerous conditions from the same health network. The data includes details of processed meat consumption.

The median consumption in this population was two portions per week in each cancer-specific case, corresponding to 100  grams in total.

Investigators found an increased risk for three of four types of cancers they examined in detail. No association with prostate cancer was found in men.

The Medpage Today report says the estimated risk for breast cancer in the current study is marginally higher than the population-wide risk found in a recently published international meta-analysis and a recent US National Institutes of Health study. But the results reported here were comparable to those of other European studies.

The increased risk of endometrial cancer reported in the Italian study agreed with the increased risk found in 23,000 postmenopausal women in the US who consumed high levels of processed meat and fish. A subset of women who never used hormonal contraceptives had a higher risk of endometrial cancer, most likely because hormonal contraception is considered protective against this type of cancer.

Lead author Valentina Rosato, from the National Cancer Institute, in Milan, and colleagues found increased risk for ovarian cancer in those who consumed at least 20 grams a day of processed meat; however, other studies found a somewhat lower risk for, or weak association with, ovarian cancer.

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