Most notable is a study by Japanese scientists of the Saitama Cancer Research Institute relating the delay of cancer onset with the consumption of green tea. The study shows that early stage breast cancer spreads less rapidly in women with a history of drinking five or more cups of green tea a day. As a result, there is a lower recurrence rate and a longer disease-free period. With the evidence that green tea and EGCG, a catechin found only in green tea, are a natural and readily available inhibitor of TNF- , a gene expression which promotes the growth in cancer cells and in their surrounding tissue, it is possible for researchers to extend this idea to other various human diseases. Since EGCG has also been proven to kill cultured cancer cells without causing harm to surrounding healthy cells, green tea could be beneficial not only for cancer prevention but also in the therapy and prevention of other diseases.
Further research is needed.