An extensive evaluation of coffee's cancer-causing risk, that resulted in a reclassification, but did not prove the beloved beverage's safety, was released by the World Health Organization (WHO) Wednesday.
"Overall coffee drinking was evaluated as unclassifiable as to its carcinogenicity to humans," the report said.
Some studies showed coffee had no effect on pancreatic, breast and prostate cancers; however, for 20 other cancers, the evidence was inconclusive.
The experts also looked at mate and very hot beverages overall.
The 23 scientists who made up the International Agency for Research on Cancer (IARC), the WHO's cancer agency, looked at over 1,000 human and animal studies.
Many studies looked at research participants' coffee drinking habits over a number of years and whether they developed cancer. The majority of the studies did not distinguish between different ways of preparing or different kinds of coffee.
Although data for coffee remained inconclusive, experts did find that "drinking very hot beverages probably causes cancer of the oesophagus in humans."
Worldwide oesophageal cancer is the eighth most common cause of cancer.
"It is the temperature, rather than the drinks themselves, that appears to be responsible." said IARC Director Christopher Wild. Very hot beverages are defined as 65 degrees celsius or hotter.
A summary of the evaluations, which includes carcinogenicity classifications, was published in the Lacet Oncology.