Dichloroacetate (DCA) has been found to shrink tumors in vivo in rats, and has a plausible scientific mechanism: DCA appears to reactivate suppressed mitochondria in some types of oxygen-starved tumor cells, and thus promotes apoptosis.[4] Because it was tested for other conditions, DCA is known to be relatively safe, available, and inexpensive, and it can be taken by mouth as a pill, which is convenient. Five patients with brain cancer have been treated with DCA in a clinical trial, and the authors say that the lives of four were 'probably' extended.[5][6] However, without a large controlled trial it is impossible to say whether the drug is truly effective against cancer.[7][8]