[Aspirin and cancer: evidence of a prophylactic effect].

Due to increased life expectancy, the number of new patients diagnosed with cancer is also increasing; this requires effective and inexpensive strategies for preventing cancer. The concept of chemoprevention involves taking medication to reduce cancer risk. By re-assessing aspirin trials that were originally conducted to determine its effect on cardiovascular disease, it appeared that aspirin was associated with a reduction in the incidence of cancer as well as cancer-related mortality. The vascular benefits and risks associated with aspirin are only clinically relevant in the short term; its beneficial effects on cancer risk only become apparent after three years. Aspirin probably has a preventive effect on metastasis. These findings from randomised trials are consistent with results from methodologically rigorous observational studies. Until now, primary prevention in vascular disease has only proven to be cost-effective in certain risk groups. In future cost-effectiveness analyses, the beneficial effect of aspirin on cancer risk needs to be taken into account.