Study will assess effect of tomato oil on precancerous prostate changes

Lycopene, an antioxidant commonly found in tomatoes and tomato-based products, is commonly perceived to reduce the risk of developing prostate cancer.

A new study at Northwestern University seeks to determine whether natural tomato oil with a high concentration of lycopene may reverse or delay progression of high-grade prostatic intraepithelial neoplasia (HGPIN), a condition in which abnormal cells form within the prostate and which is the strongest risk factor yet identified for the development of prostate cancer.

The study is headed by Peter Gann, M.D., professor of preventive medicine at the Northwestern University Feinberg School of Medicine and a member of the cancer epidemiology and prevention program at The Robert H. Lurie Comprehensive Cancer Center of Northwestern University.

Lycopene has been found to have anti-tumor activity in a number of laboratory studies. Also, it has been used in a number of cancer studies in humans (e.g., lung, stomach and prostate cancers) that demonstrated a lower cancer rate in people with a high dietary intake of lycopene.

Research has shown an over 20 percent reduced risk for developing prostate cancer in men who ate more cooked tomato products, such as tomato sauce. Additional studies showed that cooking tomatoes and eating them with oil substantially increases the bioavailability of lycopene.

The National Cancer Institute-sponsored study at Northwestern will use tomato extract (literally, tomato oil) from non-genetically modified tomatoes raised in Israel and specially grown to be high in lycopene content.

Results of the study will be useful for clarifying the mechanisms of action of lycopene in the prostate, for designing phase III clinical studies and, more generally, for determining the chemopreventive potential of this relatively non-toxic dietary compound. Prostate cancer is the most commonly diagnosed cancer among men in the United States, amounting to an expected 230,100 new cases and 29,900 deaths in 2004, according to the American Cancer Society.

“Prostate cancer is a rational target for chemoprevention because of its high public health burden and relatively slow growth rate,” Gann said. “Although early surgical treatment of prostate cancer might be effective, it involves substantial discomfort. This, plus the wide variability in the biological behavior of prostate cancer, makes overtreatment a persistent and serious concern,” Gann said.

To qualify for the lycopene HGPIN study, participants must be men age 40 and older; have had a biopsy indicating HGPIN without cancer within the last two years; be ambulatory, capable of self-care and able to perform light or sedentary work; be willing to limit intake of lycopene-containing foods, as well as supplements containing lycopene during the study period; have no prior cancer (except basal cell or squamous cell skin cancer) or complete remission for at least five years.