"Treating Prostate Cancer with Green Tea"
Green tea has been called nature’s defense against cancer.
Population studies linking green tea consumption with lower cancer risk
have led some to advocate for the incorporation of green tea into the diet—
after all, what’s the downside?
However, population studies can’t prove cause and effect.
It’s not possible to determine whether green tea
actually prevents cancer in people, until you put it to the test.
Prostate cancer is preceded by a precancerous condition
known as intraepithelial neoplasia.
Within 1 year, about 30% of such lesions turn into cancer.
Because no treatment is given to patients until cancer is diagnosed,
what a perfect opportunity to try green tea.
So, 60 men with precancerous prostate intraepithelial neoplasia were randomized
into either a green tea group or a placebo group.
It’s hard to make a convincing placebo tea; so, they used green tea pills—
roughly equivalent to about 6 cups of green tea a day—
compared to sugar pills.
Six months into the study, they took biopsies from everyone,
and in the placebo group, 6 of the 30 developed cancer by the halfway point,
and then 3 of the remaining 24 by the end of the year.
So, 9 out of 30 in the placebo group developed cancer or 30%,
which is what normally happens when you don’t do anything:
about 30% go on to develop cancer within the first year.
But, in the green tea group, none developed cancer within the first 6 months,
and only 1 by the end of the year.
So, only one out of 30, nearly ten times less than the placebo group:
the first demonstration that green tea compounds could be very effective
for treating premalignant lesions before prostate cancer develops.
And, even a year later, after they stopped the green tea,
nearly 90% of the original green tea group remained cancer free,
while more than half of the placebo group developed cancer.
This suggests that the benefits of the green tea may be long lasting,
overall a nearly 80% reduction in prostate cancer. That is pretty impressive.
What if you already have prostate cancer?
A proprietary green tea extract supplement was given to 26 men
with confirmed prostate cancer
for an average of about a month before they had their prostates removed
and there was a significant reduction in a number of cancer biomarkers
such as PSA levels, suggesting a shrinkage of the tumor,
but there was no control group and the study was funded by the supplement company itself.
When an independent group of researchers tried to replicate the results in a randomized,
double-blind, placebo-controlled trial they failed to find any statistically significant improvement.
So, maybe green tea is only effective in the precancerous state
but not powerful enough to impact overt prostate cancer.
Certainly didn’t seem to help for advanced metastatic cancer in the two studies that tried it.
And recently, doubt has been cast on the precancerous results.
When researchers tried to replicate it, the green tea extract group only seemed to
cut prostate cancer development about in half, which,
because of the small number of people in the study
may very well have happened just by chance.
So, where does that leave us?
Unfortunately, green tea extract pills are not without risk—
there’s been about a dozen case reports of liver damage associated with their use;
and so, until there’s more solid evidence of benefit I’d stick with just drinking the tea.
OK, green or black?
A recent study that randomized about a hundred men with prostate cancer to consume 6 cups
a day of green or black tea found a significant drop in PSA levels
and NF-kB in the green tea group but not the black tea or control groups.
NF-kB is thought to be a prognostic marker for prostate cancer progression;
and so, the green tea appeared to work better than the black.