Francesca Bravi, MD, of the Istituto di Ricerche Farmacologiche Mario Negri in Milan, Italy, and colleagues surveyed 767 people with renal cell carcinoma, the most common kidney cancer, and 1,534 who did not have kidney cancer. All were patients at Italian hospitals.

The interviews, which were conducted between 1992 and 2004, focused on the patients' consumption of 78 foods and drinks during the preceding two years.

Although they found that the kidney cancer patients were likely to have the highest intakes of bread, and the patients who did not have renal cell carcinoma were likely to consume the most vegetables, poultry and processed meats, the researchers did not suggest that a certain diet causes or prevents the disease.

However, they did speculate that a diet that emphasizes refined cereals and omits vegetables might play a negative role.

They found no relationship between renal cell carcinoma and coffee, tea, soup, eggs, red meat, fish, cheese, potatoes, fruit, desserts or sugars.

The researchers adjusted for family history of kidney cancer, smoking habits and alcohol consumption. They also calculated the patients' BMIs (body mass indexes) based on their height and weight.

Marji McCullough, a registered dietitian and spokesperson for the American Cancer Society, questioned the study, particularly since patients were asked to remember what they had eaten over a two-year period. She suggested that the focus in prevention should be on known risk factors.

"We know that avoiding tobacco and maintaining an ideal body weight are two ways individuals can modify their risk of developing kidney and many other cancers," she said.