More and more research supports the findings that Aspirin (acetyl salicylic acid) has a significant anti-tumoral effect. Initially, its effects where thought to be caused by its influence of an enzyme called COX-2 but todays research confirms its effect through the acidic extracellular environment of cancers. This characteristic opens up the possibility of selectively targeting cancer cells using acetyl salicylic acid.

Although the superior clinical efficacy with less side effects is already well established its use is still limited to some centers only.