Omar Kucuk, MD, and colleagues at the Barbara Ann Karmanos Cancer Institute in Detroit studied 26 men who had prostate cancer and were waiting to have surgery. For three weeks before surgery, the men were randomly assigned to receive either two daily capsules of tomato extract containing 15 milligrams of lycopene, or a placebo. After removal, the men's prostate glands were examined to see if there were any differences between the two groups.

The researchers presented the results of their study at the annual meeting of the American Association for Cancer Research held recently in Philadelphia, Penn. They reported several differences were found between the two groups they studied. Among the 15 men who had taken the lycopene supplements, five had precancerous lesions classified as small or limited, and 10 had more advanced, widespread lesions. All 11 men in the control group had advanced lesions. Because the two groups probably had a similar distribution of lesions before the study, the lycopene may have caused the drop into a lower category for a third of the men in the group receiving supplements, Dr. Kucuk said.

Researchers also found their tumors were less likely to have spread beyond the prostate in the men who had taken lycopene. Blood levels of serum PSA (prostate-specific antigen), a marker reflecting the amount of prostate cancer present, were down about 18 percent in the lycopene group and increased by about 14 percent in the untreated group. And, the cancer cells in the treated group of men appeared to be growing less rapidly and dying to a greater degree than the cancer cells of the men in the control group.

The study was the first ever conducted on the use of lycopene by men awaiting prostate surgery, and its positive, although preliminary, results are noteworthy, Dr. Kucuk said. "We think it warrants further investigation," he said. Other studies have shown an association between consumption of tomato products and a decreased risk of prostate cancer, but this study was the first to look at the possibility that lycopene could help treat as well as prevent prostate cancer.

"We need to do many more and larger studies," Dr. Kucuk said. Among the questions to be answered: What is the optimal dose of lycopene? Is it in fact lycopene, or something else in tomatoes (such as vitamin C or beta-carotene), that affects the development of cancer?

Scientists must also study the best method for consuming lycopene. Simply eating more tomatoes is not a practical solution, because one capsule like those used in this study equals two pounds of tomatoes, Dr. Kucuk said. Also, lycopene from fresh tomatoes is not absorbed as well as lycopene in tomato paste or other processed forms. Dr. Kucuk and his colleagues also hope to study whether lycopene might be helpful in treating other forms of cancer, such as head and neck, lung, bladder, or cervical cancer.

More extensive study of lycopene is needed because large, lengthy studies often produce results different than were expected based on the preliminary findings of a small study, said Michael Thun, PhD, vice president of epidemiology and surveillance research for the American Cancer Society. Although the preliminary results are very encouraging, more research must be done to find out whether lycopene treatment before surgery has any impact on long-term survival, whether continuing treatment after surgery is beneficial, and what doses are most effective.