A recent German article notes the cytotoxic properties of constituents of two Chinese herbs, one commonly used as an anti-parasitic herb, the other as a circulatory tonic and regulator. Although it seems like we pay a lot of attention to the potential cell kill factor of alkaloids present in herbs, there are many more application of herbs in cancer therapy. The author of this study has also published a paper on the inhibition of multi-drug resistance by several chinese herbs. Certain cancers are commonly resistant to conventional treatment, or become resistant to cytotoxic and other conventional or herbal interventions. Certain herbs can, when employed concurrently with other therapies, increase the effectiveness of the therapy by keeping the cancer from resisting it.
 
Phytochemistry and pharmacogenomics of natural products derived from traditional chinese medicine and chinese materia medica with activity against tumor cells
Efferth et al Molecular Cancer Therapeutics 7, 152-161, January 1, 2008. doi: 10.1158/1535-7163.MCT-07-0073
 
Activity of Drugs from Traditional Chinese Medicine toward Sensitive and MDR1- or MRP1-Overexpressing Multidrug-Resistant Human CCRF-CEM Leukemia Cells*
Efferth et al Blood Cells, Molecules, and Diseases Volume 28, Issue 2, March 2002, Pages 160-168