• World Health Organisation's cancer arm made two announcements this week: one welcome and one not so welcome.
• First, it announced there was no conclusive evidence to show coffee increases cancer risk. This is a reversal of the 1991 conclusion, when the carcinogenicity of coffee was first tested, that classified the drink as being "possibly carcinogenic to humans".
•  

• Coffee won't give you cancer, unless it's very very hot, then it might

• 
  
• 
• 
• File photo
• The World Health Organisation's cancer arm made two announcements this week: one welcome and one not so welcome.
  First, it announced there was no conclusive evidence to show coffee increases cancer risk. This is a reversal of the 1991 conclusion, when the carcinogenicity of coffee was first tested, that classified the drink as being "possibly carcinogenic to humans".
  
  RELATED STORIES
•  

 

Prospective studies involve obtaining data about, for instance, smoking, drinking and dietary practices of typically half to one million people. When monitored over a decade or more, a few hundred may be diagnosed with bladder cancer. Their coffee drinking and other data may be compared with that data for others in the larger group not diagnosed with bladder cancer.
In general, prospective studies sometimes confirm case-control studies about agents considered carcinogenic. But in the case of coffee drinking, recently conducted prospective studies failed to indicate increased risk of bladder cancer or cancer at any other site correlated with coffee intake.
Some findings even suggest coffee reduced risk of some cancers, such as liver cancer. To use the formal IARC language, coffee drinking is unclassifiable as a human carcinogen.

Very hot drinks

Also dating back to 1991 was a determination that drinking hot mate - a tea-like infusion common in South America - was probably carcinogenic to humans. It was linked to oesophageal cancer.
Interestingly, in the early 1970s, incidence of oesophageal cancer was found to vary by as much as a hundred-fold between different communities living south of the Caspian Sea (in modern-day Iran). The consumption of very hot drinks was implicated in this difference.

RELATED STORIES