This week’s 3-part blog detailed a recent, widely publicized
study that suggested that fish and fish oil consumption caused aggressive
prostate cancer. We pointed out several
flaws in the study’s methodology that undermined this conclusion, and Dr. Block
provided his recommendations for fish/fish oil, not only in light of this study,
but in the context of other relevant research.
Today’s blog will discuss a new prostate cancer study that
shows a very different diet/lifestyle connection to aggressive prostate cancer
than the study we reference above suggested.
The results may surprise you! (although they didn’t surprise us here at
the Block Center!)
A study published this summer by Lenore Arab and colleagues
at UCLA assessed weight, diet, exercise, sodium and alcohol intake in over 2000
prostate cancer patients in Louisiana and North Carolina, with approximately an
equal numbers of Caucasian and African-American men. The particular concentration on
African-American men was included because African-American men are diagnosed
with prostate cancer at younger ages and have more aggressive disease than
other ethnic groups. The strategy of
this study was to investigate what lifestyle factors are associated with
aggressive versus low-grade prostate cancer by comparing the diet and exercise
habits of prostate cancer patients to recommendations for cancer prevention
made in 2007 by the World Cancer Research Fund, which are based on over 500
studies of lifestyle and cancer.
The prostate cancer patients were interviewed to find out
their diet and exercise habits, and then they were compared to the prevention
recommendations. Here are the
recommendations that the study used:
- Be as lean
as possible without being underweight – your body mass index or BMI should be
between 21 and 23 (most sources designate normal BMI as 20-25). - Engage in at
least 60 minutes of moderate activity, or 30 minutes of vigorous activity
daily. - Limit
consumption of energy-dense (high calorie) foods. - Avoid sugary
drinks, including fruit drinks and juices, sodas, and sugar in coffee or tea. - Eat at least
5 servings a day of nonstarchy vegetables and fruits daily (e.g., French fries
don’t count towards you non-starch vegetable intake!). - Eat at least
25 grams of whole grains and cereals or legumes per day. - Eat less
than 500 grams (about 1 pound) of red meat per week. - Limit
alcohol to 2 drinks per day for men and 1 for women. - Limit sodium
intake to less than 2.4 grams per day, about 1 teaspoon.
Based on their interviews, patients were awarded 1 point for
each recommendation if they were completely in line with it. In some cases, they could get half a point if
they adhered partially to it, for instance, by getting 30 to 60 minutes of
exercise daily, or 15 to 30 minutes of vigorous exercise. If a patient adhered perfectly to each
recommendation, they could get a total of 9 points. The study didn’t mention how many patients
received perfect scores, but it could not have been too many, since only 5%
complied with the recommendation to maintain a BMI of 21-23, and the average
amount of exercise was only 10 minutes per day!
Once every patient had been scored, the study computed
average adherences, and then compared the degree of adherence to the likelihood
of having aggressive versus low-grade prostate cancer. Overall, the result was definitely
significant. For every additional point
in the adherence score, risk of aggressive prostate cancer declined by
13%. The researchers also found that
patients who had a total adherence score of less than 4 were 38% more likely to
have aggressive prostate cancer than those whose scores were more than 4. So, following cancer prevention guidelines
does, in fact, help to prevent aggressive prostate cancer. They also noted that smoking, which was not
included in the adherence calculation for this study, was associated with
aggressive cancer risk.
The researchers also analyzed which of the particular
recommendations were the most relevant for reducing prostate cancer risk. Three major risk factors were found in this
analysis. For both Caucasians and
African-Americans, limiting the energy density of foods reduced risk of
aggressive disease by 29%, and eating less than 500 grams of red meat reduced
risk by 23%. For the African-American
patients, eating less red meat reduced risk even more, by 29%. Eating less than a teaspoon of sodium was
also significantly correlated with a 36% lower risk.
Now, these authors don’t reduce the prostate cancer
recommendations to energy density, red meat and sodium! Their overall results don’t suggest that
these are the only factors that are relevant to reducing prostate cancer risks,
since it was the men who complied with fewer than 4 of the recommendations who
had the really noticeable 38% increase in risk.
They point out that high consumption of vegetables, fruits, legumes and
whole grains is likely a major reason why the men who ate less red meat wound
up with lower risks of aggressive cancer.
Eating vegetables, fruits, legumes and whole grains is also a
significant strategy for lowering the energy density of your diet, one of the
major ways to reduce aggressive cancer risk.
Other ways to reduce energy density include avoiding foods that are high
in fat (which has more calories per gram than protein or carbs) and excluding
foods that are high in sugar and other refined carbs. Avoiding red meat and excess salt are
certainly important, but they are not the whole picture. The whole picture is that men wishing to
avoid aggressive cancers should try their best to adhere to as many of the
prevention guidelines as they can. We
also suggest that these guidelines are appropriate for prostate cancer patients
hoping to avoid progression of their disease.
While some factors, such as those causing genetic mutations, may not be
as important once a cancer gets started, your biochemical environment, or
terrain, can promote cancer growth through processes such as inflammation,
stress hormones and excess blood sugar and insulin.
A final note: another
study came out this week, which was a followup of an earlier randomized trial
of the drug finasteride (Proscar) in preventing prostate cancer. Like fish oil, finasteride was under
suspicion for increasing risk of aggressive prostate cancer, although it
decreased risk of low-grade disease by nearly 5% (10.5% low-grade disease in
finasteride patients, 14.9% in the placebo group). This study confirmed a slightly higher risk
of aggressive prostate cancer in patients taking finasteride versus placebo
patients (3.5% versus 3.0%). However,
interestingly, although there were differences in the incidence of prostate
cancer, after 18 years of follow-up, there was no significant difference in
survival of the finasteride and placebo groups, despite the slightly higher
incidence of aggressive disease in the finasteride group. Of course, there may have been much more
distress, surgery and other medical intervention among men with aggressive disease
as well. Men who are interested in preventing
prostate cancer through using finasteride should talk to their doctors about
it, though, since significant side effects are possible from this drug,
especially consequences on one’s sexual life.
On the other hand, though a lifestyle overhaul is certainly more
difficult than simply popping a pill – and may not be quite as effective if
it’s done half-heartedly – the major “side effects” of adhering to cancer
prevention guidelines are a reduced risk of all cancers, and a reduced risk of
cardiovascular disease as well! And
that’s a deal that should be attractive to all of us!
For more information on The Block Center for Integrative Cancer Treatment, call (847) 230-9107 or visit BlockMD.com.