Relative potency of green tea extract fractions on various cancer cells
 

http://ecam.oxfordjournals.org/cgi/content/full/3/2/237
Epicatechins Purified from Green Tea (Camellia sinensis) Differentially Suppress Growth of Gender-Dependent Human Cancer Cell Lines


The first part of this paper deals with prostate & ovarian cancer cells treated with one of the 4 fractions of green tea extract: epicatechin (EC), epigallocatechin (EGC), EC 3-gallate (ECG) or EGC 3-gallate (EGCG).

Table 3 in the Discussion section provides a summary of the relative potency of the 4 fractions of green tea extract on various cancer cells including from breast & brain.
EGCG appears to be the most potent on several breast cancer cell lines.