Randomized Trial with Fruits and Vegetables in Prevention of Cancer

Abstract

Along with tobacco use, diet has the greatest impact on the development of human cancer. Within the broad category 'diet', the consumption of fruits and vegetables apparently plays a dominant role. Considerable efforts have been made to prove the preventive effect of different kinds of fruits and vegetables but randomized chemoprevention trials have failed to prove this presumed effectiveness of their single ingredients. The conclusive demonstration of a cancer-protective effect of a high consumption of fruits and vegetables is considered to be impractical. However, current historical changes in Europe offer a unique opportunity to conduct such a randomized trial in specific European countries. This study describes the nutritional situation and the conditions of the health system in the Baltic countries as appropriate geographic areas and demonstrates some basic design issues of the trial for three variants of outcome assumptions. A realistic assumption would be that a trial needs about 30 t 000 participants, an intervention period of 10 years and a subsequent follow-up time of 20 years. Annual costs could range between $5 and $10 million. A high intake of fruits and vegetables should be proven scientifically as a valid tool for cancer prevention. For a comparably short period the Baltic countries offer a time-window for a randomized trial. It is unlikely that the costs of such a trial would considerably exceed the costs of the available chemoprevention trials.