Maté drinking and oral and oro-pharyngeal cancer: a systematic review and meta-analysis.

In Latin America, maté is consumed as a beverage regularly. Among the cancers that are associated with maté drinking is oral and oro-pharyngeal cancer, incidence of which is high in the region. In order to further understand this association between maté drinking and the risk of oral and oro-pharyngeal cancer, we performed a systematic review and meta-analysis of related studies. All relevant studies published in English as original articles up to June 2009 were identified through a literature search using PubMed and Medline and by reviewing the references from the retrieved articles. Four case-control studies done in Latin America were identified. There were 879 maté users and 1128 non- or low-maté users in those studies with a total of 566 oral and oro-pharyngeal cancers. The adjusted association between maté drinking and oral and oro-pharyngeal cancer was significant within 3 of those studies. Meta-analysis yielded a significant summary odds ratio (OR) of 2.11 (95% confidence interval=1.39-3.19). Population Attributable Risk for maté drinking was 16%. While the epidemiological data indicate that maté users have an increased risk of oral and oro-pharyngeal cancer, little is known about whether this increased risk is due to the high temperature of the beverage when it is consumed or due to certain carcinogenic constituents that are present in maté. More human and animal studies are needed before a conclusion can be made on the oral and oro-pharyngeal carcinogenic risk of maté to humans.