Groene thee remt prostaatkanker*
Uit een kleine Amerikaanse clinical trial blijkt dat groene thee extracten bij prostaatkankerpatiënten aanzienlijke dalingen geeft aan markers in het bloed die wijzen op de progressie van de ziekte. In de studie kregen 26 mannen, die allen de diagnose
prostaatkanker gekregen hadden en op de wachtlijst stonden voor een radicale prostatectomie, dagelijks 4 capsules groene thee extract (vergelijkbaar met 12 koppen groene thee per dag) en dat gemiddeld 34 dagen lang. In het bloed werden aanmerkelijke reductie gevonden van de markers HGF (Hepatocyte groeifactor), VEGF (Vasculaire endotheelcel groeifactor) en PSA. Ook andere biomarkers waren positief beïnvloed, leverfuncties waren normaal en er waren nauwelijks of geen bijwerkingen.
Green Tea Slows Down Prostate Cancer Progression Significantly
A study carried out by researchers in the Feist-Weiller Cancer Center, LSU Health Sciences Center-Shreveport, USA, found that men with prostate cancer who consumed the active compounds found in green tea had considerable reduction in serum markers predictive of prostate cancer progression. The study has been published in Cancer Prevention Research, an American Association for Cancer Research journal.
James A. Cardelli, Ph.D., professor and director of basic and translational research in the Feist-Weiller Cancer Center, LSU Health Sciences Center-Shreveport, said "The investigational agent used in the trial, Polyphenon E (provided by Polyphenon Pharma) may have the potential to lower the incidence and slow the progression of prostate cancer."
Cardelli said that green tea, the second most popular drink on the planet, has shown health benefits which included a reduced incidence of prostate cancer. Nevertheless, some human trials had come up with conflicting results. Trials so far had only looked at the clinical efficacy of green tea consumption, rather than evaluating the change in biomarkers - biomarkers may predict prostate cancer progression.
Cardelli and team carried out an open-label, single-arm, Phase II clinical trial to find out what effect short-term supplementation with green tea's active compounds might have on serum biomarkers in patients with prostate cancer. The biomarkers include HGF (hepatocyte growth factor), VEGF (vascular endothelial growth factor) and PSA (prostate specific antigen). HGF and VEGF are good prognostic indicators of metastatic
disease.
26 men, aged 41 to 72 years were included in the trial. They had all been diagnosed with prostate cancer and scheduled for radical prostatectomy. They were given four capsule containing Polythenon E daily up to the day of surgery. Four capsules are equivalent to about 12 cups of green tea, Cardelli said. The study for 25 of the 26 patients took 12 to 73 days, with a median time of 34.5
days.
The scientists found considerable reduction in serum levels of HGF, VEGF, and PSA after treatment. Some of the patients had reductions of over 30%, the researchers explained. Liver function remained normal, other biomarkers were also positively affected, and side-effects were minimal.
A recent 12-month clinical trial carried out in Italy found that consumption of green tea polyphenols lowered the risk of developing prostate cancer in men with high-grade prostate intraepithelial neoplasia (HGPIN).
Cardelli said "These studies are just the beginning and a lot of work remains to be done, however, we think that the use of tea polyphenols alone or in combination with other compounds currently used for cancer therapy should be explored as an approach to prevent cancer progression and recurrence."
William G. Nelson, V., M.D., Ph.D., professor of oncology, urology and pharmacology Johns Hopkins Kimmel Cancer Center, believes the reduced serum biomarkers of prostate cancer may be due to some kind of benefit relating to green tea components. "Unfortunately, this trial was not a randomized trial, which would have been needed to be more sure that the observed changes were truly attributable to the green tea components and not to some other lifestyle change (better diet, taking vitamins, etc.) men undertook in preparation for surgery. However, this trial is provocative enough to consider a more substantial randomized trial."
The same researchers are carrying out another trial, along with scientists from Columbia University, New York City, with breast cancer patients. They intend to carry out additional trials to identify factors that may explain why some patients responded better to Polyphenon E than others. Cardelli believes that further controlled trials should be carried out to find out whether combinations of different plant polyphenols are more effective than Polyphenon E alone.
Cardelli said "There is reasonably good evidence that many cancers are preventable, and our studies using plant-derived substances support the idea that plant compounds found in a healthy diet can play a role in preventing cancer development and progression."
"Tea Polyphenols Decrease Serum Levels of Prostate-Specific Antigen, Hepatocyte Growth Factor, and Vascular Endothelial Growth Factor in Prostate Cancer Patients and Inhibit Production of Hepatocyte Growth Factor and Vascular Endothelial Growth Factor In vitro"
Jerry McLarty, Rebecca L.H. Bigelow, Mylinh Smith, Don Elmajian, Murali Ankem and James A. Cardelli
Cancer Prevention Research,
10.1158/1940-6207.CAPR-08-0167
(Augustus
2009)
