The study involved 50 men who had undergone surgery or radiation but quickly experienced increases in prostate-specific antigen or PSA, a biomarker that indicates the presence of cancer. UCLA researchers measured "doubling time," how long it takes for PSA levels to double, a signal that the cancer is progressing, said Dr. Allan Pantuck, an associate professor of urology, a Jonsson Cancer Center researcher and lead author of the study.
Doubling time is crucial in prostate cancer, Pantuck said, because patients who have short doubling times are more likely to die from their cancer. The average doubling time is about 15 months. In the UCLA study, Pantuck and his team observed increases in doubling times from 15 months to 54 months, an almost four-fold increase.
"That's a big increase. I was surprised when I saw such an improvement in PSA numbers," Pantuck said. "In older men 65 to 70 who have been treated for prostate cancer, we can give them pomegranate juice and it may be possible for them to outlive their risk of dying from their cancer. We're hoping we may be able to prevent or delay the need for other therapies usually used in this population such as hormone treatment or chemotherapy, both of which bring with them harmful side effects."
The study appears in the July 1 issue of Clinical Cancer Research, the peer-reviewed journal of the American Association of Cancer Research.
"This is not a cure, but we may be able to change the way prostate cancer grows," Pantuck said. "We don't know yet the specific factors behind this response - that's our next step in this research. We want to find out what cell signaling pathways might be affected, what is happening to keep PSA levels stable."
Pomegranate juice is known to have anti-inflammatory effects and high levels of anti-oxidants, which are believed to protect the body from free-radical damage. It also contains poly-phenols, natural antioxidant compounds found in green tea, as well as isoflavones commonly found in soy, and ellagic acid, which is believed to play a role in cancer cell death.
"There are many substances in pomegranate juice that may be prompting this response," Pantuck said. "We don't know if it's one magic bullet or the combination of everything we know is in this juice. My guess is that it's probably a combination of elements, rather than a single component."
The levels of PSA in men immediately following treatement should be undetectable, Pantuck said. If PSA can be detected, it's an indication of an aggressive cancer that is likely to progress. The men in Pantuck's study all had detectable PSA following treatment. Of the 50 men enrolled, more than 80 percent experienced improvement in doubling times.
Conventional treatment for men with recurrent prostate cancer includes hormonal therapy, a chemical castration which removes testosterone from the system. Men treated with hormonal therapy can experience hot flashes, osteoporosis, fatigue, depression, muscle wasting, loss of libido and erectile dysfunction. If drinking pomegranate juice can delay or prevent the need for hormonal therapy, patients would experience a better quality of life for a longer time, Pantuck said.
The patients in Pantuck's study experienced no side effects and none of the participants had cancers that metastasized during the study.
Pantuck, along with UCLA colleagues including Dr. Arie Belldegrun, professor and chief of urologic oncology, and Dr. David Heber, professor and director of the Center for Human Nutrition, first began research on pomegranate juice in prostate cancer about six years ago, conducting preclinical research in cell cultures and in animals. Those studies showed pomegranate juice slowed the growth of prostate cancer, Pantuck said.
The data was impressive enough to test pomegranate juice in clinical trials, Pantuck said. To confirm their findings, a larger Phase III study, headed up by UCLA, will be conducted at ten centers across the county. UCLA is the only Southern California center involved in the study. For more information on the Phase III trial, call (310) 825-5538.
Pantuck said he has men on the study more than three years out who are not being treated for prostate cancer other than drinking pomegranate juice and their PSA levels continue to be suppressed.
"The juice seems to be working," he said.
The study, performed at the Clark Urology Center, was funded by the Stewart and Lynda Resnick Trust. The Resnicks own POM Wonderful, which provided the juice from the Wonderful variety of pomegranate for the study.
UCLA's Jonsson Comprehensive Cancer Center comprises more than 240 researchers and clinicians engaged in research, prevention, detection, control, treatment and education. One of the nation's largest comprehensive cancer centers, the Jonsson center is dedicated to promoting research and translating the results into leading-edge clinical studies. In July 2005, the Jonsson Cancer Center was named the best cancer center in the western United States by U.S. News & World Report, a ranking it has held for six consecutive years.