 Other
Source
General lifestyle
recommendations to prevent cancer include:
Avoid tobacco
Be physically active
Maintain a healthy weight
Eat a diet rich in fruits,
vegetables, and whole grains, and low in saturated/trans fat
Limit alcohol
Protect against sexually
transmitted infections
Avoid excess sun
Get regular screening
(breast, cervix, prostate, colon-rectum)
Specific factors associated with
cancer risk include the following:
.
The association of dietary fat, fruits,
vegetables, and fiber with cancer risk is largely unconfirmed.
Red meat
consumption may promote colorectal
cancer and a high intake of
tomatoes probably
decreases prostate cancer risk.
Vitamin D
may reduce the risk of colorectal and prostate cancer.
Calcium intake,
at a minimum of 700 mg/day, may protect against colorectal cancer but
high calcium intake (>2000 mg/day) increases risk for prostate cancer.
Folate
in diet has been associated with a decreased risk of colon and breast
cancer, especially in women who drink alcohol; data on folic acid or
multivitamin supplementation are inconsistent.
Alcohol
intake, even in moderate quantities, increases the risk for colon,
breast, esophageal and oropharyngeal cancer.
Physical activity
is inversely related to risk for colon and breast cancer. Excess weight
increases the risk of multiple cancers.
Other web sites: AHRQ Guidelines,
Diet and Nutrition,
HSTAT Guide to
Prevention 3rd Ed,
NCI Screening,
NCI Trial Page,
US Prevent
Task Force 2nd Ed There have been numerous studies
looking at diet supplements which might lower the risk of cancer (studies on
beta-carotene, selenium, Vitamin E or aspirin type drugs.) Certain hormone
drugs
(Tamoxifen in breast cancer and Proscar in prostate cancer) have been shown to be
effective, but most of the other studies have not shown positive
results as noted in the recent studies below.
A recent study
showed no significant benefit from B vitamins in preventing cancer in women
(go here).
Low-Dose Aspirin and Vitamin E. Challenges
and Opportunities in Cancer Prevention
Eric J. Jacobs, PhD; Michael J. Thun, MD JAMA. 2005;294:105-106.
This issue of JAMA includes 2 articles from the Womens Health Study (WHS). This
10-year long, placebo-controlled, randomized trial of low-dose aspirin and vitamin E
included nearly 40 000 predominantly middle-aged women with no history of cancer or
cardiovascular disease.3 The WHS used a 2 x 2 factorial design to evaluate the effects of
low-dose aspirin (100 mg) taken every other day and 600 IU of
vitamin E (in the form of natural-source {alpha}-tocopherol), also taken every
other day. Neither alternate-day, low-dose aspirin nor vitamin E
showed any evidence of efficacy in reducing overall cancer incidence or mortality.
With respect to noncancer outcomes, notable findings for low-dose aspirin included a
reduction in stroke risk, no apparent effect on myocardial infarction, and an increased
risk of gastrointestinal bleeding requiring transfusion. Vitamin E had no apparent
effect on either cardiovascular disease incidence or on gastrointestinal bleeding.
Could long-term, low-dose aspirin treatment (?150 mg/d) produce any important reduction in
risk of cancer? The WHS provides strong evidence that alternate-day, low-dose aspirin
treatment does not, or at least not for women within the first 10 years of treatment.
There was no suggestion of reduced risk for overall cancer incidence, breast cancer
incidence, colorectal cancer incidence, or cancer mortality. This remained true even in
analyses restricted to the second 5 years of follow-up, when participants in the
intervention group had already accrued a minimum of 5 years of aspirin exposure. To our
knowledge, no other studies, either randomized trials or observational studies, have
evaluated the effect of alternate-day, low-dose aspirin on cancer risk. A previous,
considerably smaller, randomized trial examined alternate-day use of 325 mg of aspirin and
found no association with colorectal cancer incidence. However, the 5-year intervention
period of this trial may have been too short to produce clear effects. Results from the
WHS do not entirely rule out the possibility that taking low-dose aspirin every day,
rather than every other day, could have some cancer prevention benefits. Evidence about
the potential effects of daily low-dose aspirin on cancer risk is limited and includes
some inconsistent findings. For example, a randomized trial found a dose of 81 mg/d
reduced risk of colorectal polyp recurrence. However, analyses of pharmacy databases
in the United Kingdom and Denmark found no association between low-dose aspirin use and
colorectal cancer incidence.
The null results from WHS with respect to alternate-day, low-dose aspirin do not refute
previous evidence that moderate or high doses of aspirin (?325 mg/d) may reduce the risk
of certain cancers. In numerous observational studies, regular
use of aspirin has consistently been associated with reduced risk of colon or colorectal
cancer, with most studies reporting 30% to 50% reductions in incidence.
Two randomized trials have shown that aspirin treatment reduces the recurrence of
colorectal adenomatous polyps in patients with previous polyps or colorectal cancer. Aspirin use has also been consistently associated with reduced risk of
esophageal and stomach cancer, although there are fewer studies of these cancers than of
colorectal cancer. The totality of the evidence from laboratory studies,
observational epidemiology, and randomized trials of colorectal polyp recurrence continues
to support the hypothesis that moderate or high doses of aspirin may reduce the risk of
colorectal cancer, and possibly the risk of certain other cancers as well.
The null results for vitamin E (in the form of
{alpha}-tocopherol) and cancer from the WHS add to the evidence from 2 previous trials
that even relatively long-term {alpha}-tocopherol supplementation is unlikely to
have any substantial effect on cancer risk, at least in women. An unexpected
reduction in prostate cancer incidence was observed among men randomized to
{alpha}-tocopherol in the Alpha-Tocopherol Beta Carotene (ATBC) trial, a study that
included only male smokers. However, this association was not observed in the Heart
Outcomes Prevention EvaluationThe Ongoing Outcomes (HOPE-TOO) trial, in
postintervention follow-up of the ATBC trial, or in 2 large prospective
observational studies, and may have been a result of chance. Although ongoing
randomized trials will eventually provide further information, the promise of
{alpha}-tocopherol as a cancer prevention agent appears to be dimming.
Should the null results with respect to cancer from this large, well-conducted, long-term
randomized trial, or from other chemoprevention trials, be considered discouraging news
for cancer chemoprevention in general? There have been some
successes in cancer chemoprevention, such as the use of tamoxifen to prevent breast cancer
in high-risk women. However, currently, no agent has
been shown to do for cancer what statins do for cardiovascular disease, namely
substantially and relatively safely reduce disease occurrence in individuals not at
especially high risk. Pharmacological primary prevention of diseases as
heterogeneous as cancer is inherently difficult. Randomized trials of cancer
chemoprevention will undoubtedly produce many null results. Nevertheless, continued
systematic research on cancer chemoprevention, including long-term randomized trials of
carefully chosen agents, is essential given the large potential benefits. At the same
time, it is unrealistic to expect the discovery of an agent that will produce substantial
reductions in overall cancer rates in the immediate future.
With this in mind, it is important to remember that effective
methods for reducing cancer incidence and mortality have already been discovered, but are
underapplied. For instance, colorectal cancer screening is greatly underused,
providing an important cancer prevention opportunity for physicians and other
health care professionals. Reducing tobacco use is essential for cancer prevention, and
strong evidence indicates that policy measures, such as increases in tobacco excise taxes
and clean indoor air regulations, are effective in reducing tobacco use. In
addition, clinicians can play an invaluable role in cancer prevention by asking patients
about tobacco use and ensuring that patients who use tobacco receive appropriate
counseling and treatment. |