"Can Green Tea Help Treat Cancer?"
Tea consumption may reduce the risk of getting oral cancer.
Not only may the consumption of tea boost the antioxidant power
of our bloodstream, within minutes of consumption,
and decrease the amount of free radical DNA damage
throughout our systems over time,
but it can also increase the antioxidant power of our saliva
and decrease the DNA damage within the inner cheek cells of smokers,
though not as much as stopping smoking all together.
So might this help precancerous oral lesions
from turning into cancerous oral lesions?
More than a 100,000 people develop oral cancer annually worldwide,
with a 5-year overall survival rate of less than the flip of a coin.
Oral cancer frequently arises from precancerous lesions in the mouth,
which each have a few percent chance every year from turning cancerous,
so what a perfect opportunity to see if green tea can help.
Fifty-nine patients with precancerous oral lesions
were randomized into a tea group,
in which capsules of powdered tea extract were given
as well as having the lesions painted with the green tea powder,
versus a control group that essentially got sugar pills
and were painted with nothing.
Within 6 months, lesions in 11 of the 29 in the tea group shrunk,
compared to only 3 out of 30 in the placebo group.
The results indicate that tea treatment can improve
the clinical manifestations of the oral lesions.
The most important question though is,
"Did it prevent them from turning cancerous?".
Because the trial only lasted a few months they couldn’t tell,
but when they scraped some cells off of the lesions
there was a significant drop in DNA damaged cells
within 3 months in the treatment group,
suggesting that things were going in the right direction.
Ideally, though we'd do a longer study
to see if they ended up with less cancer, and while we're at it,
how about a study where they just used swallowed tea components,
since most people don’t fingerpaint with tea in their mouths.
We didn’t have such a study, though until...
we did.
Same extraordinary clinical results with some precancerous lesions shrinking away,
and the study lasted long enough to see
if fewer people actually got cancer,
but there was just as much new cancer
in the green tea group as the placebo group.
So a higher response rate— I mean, the lesions looked better,
but no improvement in cancer-free survival,
which is the whole point.
These studies were done mostly on smokers and former smokers.
What about lung cancer?
Population studies suggest tea may be protective,
but let’s put it to the test.
Seventeen patients with advanced lung cancer
given up to the equivalent of like 30 cups of green tea a day,
but no objective responses were seen.
Another study of 49 cancer patients— 21 with lung cancer—
got between 4 and 25 cups worth of green tea compounds a day
and again no benefits were found.
The only benefit green tea may be able to offer lung cancer patients
is to help lessen the burns from the radiation treatments
when applied on the skin as green tea compresses
may be able to shorten the duration of the burns.
The protective effects of green tea applied topically
was also seen in precancerous cervical lesions,
where the twice a day direct application of a green tea ointment
showed a beneficial response in nearly three-quarters of the patients
compared to only about a 10% response in the untreated control group,
which is consistent with the anti-cancer effects of green tea compounds
on cervical cancer cells in a petri dish,
but when women just got green tea extract pills to take,
the pills didn’t seem to help.
I’ve talked about the potential benefit of green tea wraps for skin cancer—
is there any other cancer where green tea actually comes in direct contact?
Yes. Colon cancer, which grows from the inner surface of the colon
that comes in contact with food and drink.
In the colon, tea compounds are fermented by our good gut bacteria
into compounds like 3,4DHPA,
which appears to wipe out colon cancer cells
while leaving normal colon cells relatively intact in vitro.
So 136 patients with a history of polyps were randomized
to get green tea extract pills or not.
Now this was a study in Japan, so everyone was already drinking green tea.
So effectively this was comparing those who drank 3 cups a day to 4 cups a day,
but a year later on colonoscopy the added green tea group
had only half the polyp recurrence,
and the polyps that did grow were 25% smaller.
That’s pretty exciting!
Why hasn’t a larger follow-up study been done since?
Perhaps due to the difficulty in raising funds for the study,
because green tea is a cheap beverage, not a pharmaceutical.
But the good news is that thanks to a major cancer charity in Germany,
researchers are currently recruiting for the largest green tea cancer trial to date
in which more than 2000 patients will be randomized.
I look forward to presenting the results when they come in.