How can oriental medicine claim to cure cancer?

TCM for cancer: What you refer as oriental medicine is traditional chinese medicine correct? Tcm has thousand years history to support its effectiveness and efficacy. A lot of "western" chemotherapy are originally found and made from natural source-i.e.Such as sea cucumber, periwinkle plant. Etc. The problem is that it is really hard to prove/explain the mechanism/ efficacy of tcm using the western standard.