Initial findings suggest that tomato lycopene — the stuff that gives tomatoes their color — may help prevent certain kinds of cancer, including prostate cancer.
A six-year study conducted by Harvard University researchers found a relationship between a diet rich in tomato-based foods and a reduced risk of certain kinds of cancer.
Intrigued by those findings, Omer Kucuk, M.D., an oncologist at the Barbara Ann Karamanos Cancer Institute in Detroit, launched a small pilot study in 1999 to try to demonstrate a biological effect from eating tomato lycopene. He took a group of 26 patients with early-stage prostate cancer who were already scheduled to undergo radical prostatectomies (removal of the prostate and biopsy of the surrounding tissue). The group was randomized by computer and divided into two groups. The control group did nothing. Patients in the test group were given 15 milligrams of tomato lycopene in capsule form twice a day for three weeks prior to surgery.
After surgery, the removed prostates were examined.
Kucuk explained, “When we tabulated the results, the group on lycopene had smaller cancers, and their cancers were confined to the prostate. The cancers in the control group were larger and went to the margins of the resection, or even beyond the gland. We also found the precancerous areas were much smaller in the group that took lycopene.”
Kucuk says there are two possible explanations for these results. First, lycopene is an antioxidant that neutralizes free radical oxygen molecules before they can damage the DNA of cells. Lycopene is the most powerful of the antioxidants and is found in great abundance in the testicles and prostate.
But Kucuk says his study was probably too short to be explained by free radical action. Instead, he theorizes that lycopene may have had an anti-inflammatory effect.
“We are looking at the role of inflammation in the growth of cancer cells,” he says. “Inflammatory molecules promote cell cancer growth. If you can prevent inflammation, maybe you prevent the growth of cancer. Antioxidants like Lycopene inhibit the enzymes that cause inflammation and may be the reason the tumors in the test group shrunk.”
Kucuk and his team also followed the prostate specific antigen, or PSA, levels of both groups. PSA is a protein present in the bloodstream of men with prostate cancer. High levels of total PSA indicate a likelihood of cancer.
“We did PSA levels on all subjects at the time they entered the study and then again right before surgery. To our surprise the individuals who took lycopene reduced their PSA by 18 percent. In the control group it went up 14 percent.”
Although this study was too small to draw definitive conclusions, Kucuk is encouraged to repeat the study on a larger test group. He will also be conducting studies on patients with advanced prostate cancer.