LEF.org: Colon cancer

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August 17, 2007

In this issue

Life Extension Update Exclusive

Usual suspects rounded up in colon cancer recurrence

Health Concern

Colorectal cancer

What's Hot

Type of fat important in reducing colorectal cancer risk

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Life Extension Update Exclusive

Usual suspects rounded up in colon cancer recurrence

Meat, fat, refined grains and desserts have again once been implicated

in perpetrating disease--this time, in colon cancer recurrence.

In research published in the August 15, 2007 issue of the Journal of the

American Medical Association, A. Meyerhardt, MD, MPH, of the

Dana-Farber Cancer Institute, Boston and colleagues evaluated the effect

of two dietary patterns on disease recurrence in 1,009 men and women

with stage III colon cancer treated with surgery and drugs. The prudent

dietary pattern consisted of high intake of fruit, vegetables, poultry

and fish, while the Western pattern was characterized by meat, fat,

refined grains and desserts. Dietary adherence scores were calculated

via responses to questionnaires completed by the subjects during and six

months following chemotherapy. Over the median 5.3 year follow up

period, 324 subjects experienced recurrence of their disease and of

these, 223 died. An additional 28 deaths without cancer recurrence were

documented.

High intake of the Western dietary pattern was associated with a

significant increase in cancer recurrence risk or death over follow up.

Men and women whose adherence to the Western diet was in the top 20

percent had 3.25 times the risk of their cancer returning, or dying from

any cause than participants in the lowest 20 percent of Western diet

intake. Adjustment for age, body mass and other factors failed to modify

the association.

There was no relationship found between cancer recurrence or death and

the prudent dietary pattern.

The authors suggest that increased insulin and insulin-like growth

factor levels resulting from greater intake of the Western pattern could

be the mechanism behind the increase in cancer recurrence. These factors

have been associated in previous research with increased tumor growth

and formation.

& ldquo;We know from previous research that diet and lifestyle influence

people & rsquo;s risk of developing colon cancer, & rdquo; Dr Meyerhardt

observed. & ldquo;This is the first large observation study to focus on

the role of diet in recurrence of the disease. Our results suggest that

people treated for locally advanced colon cancer can actively improve

their odds of survival by their dietary choices. & rdquo;

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Health Concern

Colorectal cancer

In industrialized Western societies, both polyps and colon cancer occur

more frequently due in part to diets low in fruits, vegetables,

vegetable protein, and fiber (Satia-Aboutaj J et al 2003). Fecal

mutagens are produced by certain diets such as those containing

overcooked or burnt meat or fish. Increased intake of fiber, on the

other hand, shortens the intestinal transit time, which in turn reduces

the exposure of the colorectal lining to mutagens within the stool

(Johansson G et al 1997).

Fat intake. A diet high in saturated animal fat, particularly dairy

products and red meat ( et al R 2003), increases colorectal cancer

risk (Pierre F et al 2003; Stadler J et al 1988). The digestion of fats

requires the activity of normal bile acids that irritate and damage

cells lining the colon. Consequently, bile acids activate factors

associated with abnormal growth of these cells, resulting in an

increased risk of colorectal cancer (Glinghammar B et al 1999; Suzuki K

et al 1986). The ratio between the secondary bile acid deoxycholic acid

and cholic acid may be an indicator of colorectal cancer risk (Kamano T

et al 1999). Ingesting a sensible amount of calories and maintaining a

desirable weight also play important roles in preventing colorectal

cancer (Mason JB 2002).

Red meat intake. The heterocyclic amines when meat is cooked at high

temperatures (e.g., by frying) are strongly associated with death from

colorectal cancer (Bingham SA et al 1996; Armstrong B et al 1975).

People who eat fried, well-cooked red meat more than once weekly are 2.2

times more likely to develop colorectal adenomas than are those who eat

lightly browned red meat once a week or less frequently. Dietary beef

induces, and rye bran prevents, formation of intestinal polyps (Mutanen

M et al 2000).

Folate. Low folate intake, especially when combined with alcohol

consumption and a low-protein diet, increases colorectal cancer risk

(Kato I et al 1999). Dietary folate influences DNA methylation,

synthesis, and repair. Abnormalities in these DNA processes enhance

cancer development, particularly in rapidly growing tissues such as the

colorectal mucosa (Lengauer C et al 1997; Feinberg AP et al 1983).

Higher folate intake from either dietary sources or supplements may

protect against the initiation of colorectal cancer (Giovannucci E 2002,

1998).

Selenium. Low levels of selenium correlate with the presence of adenomas

(benign tumors), whereas increased levels of selenium are associated

with reduced risk of adenomas. Intervention trials have found a

beneficial effect of selenium supplementation (Russo MW et al 1997).

http://www.lef.org/protocols/cancer/colorectal_01.htm

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What's Hot

Type of fat important in reducing colorectal cancer risk

Although high intake of fat has been associated with an increase in

cancer risk, a case-control study published in the July 15, 2007 issue

of the American Journal of Epidemiology concluded that a greater intake

of omega-3 polyunsaturated fatty acids may be protective against

colorectal cancer.

Professor Harry of the College of Medicine and Vet Medicine at

the University of Edinburgh in Scotland, and his associates paired 1,455

men and women diagnosed with colorectal cancer with an equal number of

healthy control subjects matched for age, gender and region of

residence. Lifestyle and food frequency questionnaires regarding the

year prior to diagnosis or recruitment to the study were completed by

all participants in the current analysis. Total fatty acid, as well as

saturated fatty acid, monounsaturated fatty acid, omega-6

polyunsaturated fatty acid, omega-3 polyunsaturated fatty acid,

trans-fatty acid, and trans-monounsaturated fatty acid intake was

determined. Intake levels of individual fatty acids, such as

eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were also

calculated.

Participants without colorectal cancer reported significantly lower

daily calorie intake than those diagnosed with the disease. Although

total and trans-monounsaturated fatty acid intake were associated with

increased colorectal cancer risk, adjustment for calorie intake negated

this effect. Greater intake of omega-3 fatty acids, EPA, and DHA were

dose-dependently associated with reduced colorectal cancer risk.

http://www.lef.org/whatshot/index.html#tofi