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Stay active to reduce your colon cancer risk: exercise and colon screenings may help keep your colon healthy and functioning optimally

Nov 13

Colorectal cancer is a serious threat to women–more than 26,000 women died from it in 2007, according to the American Cancer Society.

Fortunately, preventive measures can greatly reduce your risk. For example, researchers found that women who reported walking between 1 and 1.9 hours per week were 31 percent less likely to develop colon cancer than women who did not walk (International Journal of Cancer, Dec. 15, 2007).

“We know that maintaining an active lifestyle is important to both colon and overall health,” says Felice Schnoll-Sussman, MD, director of research at The Jay Monahan for Gastrointestinal Health at NewYork-Presbyterian/Weill Cornell.

Exercise for prevention

Any amount of activity is good, but more is better–in the study, women who got more than four hours of moderate to vigorous exercise per week had a 40 percent lower risk of colon cancer compared to women who got less than one hour of exercise per week.

How does exercise improve colon health?

“We do not yet understand clearly why an active lifestyle reduces the risk of colorectal cancer. Proposed mechanisms include a role in reducing obesity, reducing stool transit time, decreasing exposure of the colon to carcinogens, reducing insulin resistance, and influencing immune function,” says Dr. Schnoll-Sussman.

Screening options

Colon cancer is highly preventable–and highly curable–when recommended screenings are performed.

“It’s very important to follow screening recommendations, because early colorectal cancer usually causes no symptoms at all,” says Dr. Schnoll-Sussman.

The American Cancer Society, in collaboration with the U.S. MultiSociety Task Force and American College of Radiology, issued updated colorectal cancer screening guidelines in March 2008. For the first time, screening tests are grouped into two categories: those that primarily detect cancer early and those that detect both cancer and pre-cancerous polyps. The guidelines include a strong emphasis on prevention.

Tests that detect both pre-cancerous polyps and cancer include colonoscopy, flexible sigmoidoscopy, double-contrast barium enema, and computerized tomographic colonography (also known as virtual colonoscopy). Tests that primarily detect cancer early are stool tests, including guaiac-based and immunochemical-based fecal occult blood tests (gFOBT & FIT), and stool DNA tests (sDNA).

A colonoscopy, during which a doctor examines the entire length of the colon and rectum with a flexible, lighted tube, is the most comprehensive of the screening options–it allows for both the detection and removal of polyps in one exam.

For those with an average risk, colorectal cancer screening should begin at age 50. Those with certain risk factors, such as a personal or family history of colorectal polyps or cancer, need to talk to their doctor about getting screened at a younger age and at more frequent intervals.

WHAT YOU CAN DO

* Consult your doctor about an exercise regimen that is right for you. Thirty minutes of exercise five or more days a week may be beneficial for colon health.

* Eat a diet high in fruits and vegetables and low in red and processed meats.

* For more on colorectal cancer screening options, visit the American Cancer Society’s Web site, www.cancer.org.

COPYRIGHT 2008 Belvoir Media Group, LLC
COPYRIGHT 2008 Gale, Cengage Learning

colon, colon cancer, colorectal cancer, exercise     0 Comments

How Stress Affects the Immune System

Sep 26

We have known for some time that stress affects our immune systems. Many studies have shown that stress can suppress the immune system, but other studies have shown boosts in the immune system under stress. A July 2004 meta-analysis of 293 studies conducted over the past 30 years puts the pieces of the puzzle together. Psychologists Suzanne Segerstrom, Ph.D., and Gregory Miller, Ph.D. found the following:

  • Stress does indeed affect the immune system in powerful ways.
  • Short-term stressors boost the immune system. It seems that the “fight or flight” response prompts the immune system to ready itself for infections resulting from bites, punctures, scrapes or other challenges to the integrity of the body.
  • Chronic, long-term stress suppresses the immune system. The longer the stress, the more the immune system shifted from they adaptive changes seen in the “fight or flight”1 response to more negative changes, first at the cellular level and later in broader immune function. The most chronic stressors – stress that seems beyond a person’s control or seems endless – resulted in the most global suppression of immunity. Almost all measures of immune system function dropped across the board.
  • The immune systems of the elderly or those already sick are more subject to stress-related changes.

In reaching these conclusions the authors looked at the effects of the various stressors on different immune responses, such as “natural” and “specific” immunity. They summarized the results of the studies that looked at each of these types of stress:

Natural immunity produces quick-acting, all-purpose cells that can attack many pathogens; they bring fever and inflammation.

The body takes a few days to mount a more specific attack on particular invaders with specific immunity. This response includes lymphocytes (T-cells and B cells). Specific immunity has both cellular responses, which fight pathogens that get inside cells (such as viruses), and humoral responses, which fight pathogens that stay outside cells, such as bacteria and parasites. Segerstrom and Miller were able to assess how different types of immune response correlated with different types of stress because researchers have identified the blood markers of these different immune responses.

They divided stressors into different types:

Acute time-limited stressors: lab challenges such as public speaking or mental math.

Brief naturalistic stressors: real-world challenges such as academic tests.

Stressful event sequences: a focal event such as loss of a spouse or major natural disaster gives rise to a series of related challenges that people know at some point will end.

Chronic stressors: pervasive demands that force people to restructure their identity or social roles, without any clear end point – such as injury resulting in permanent disability, caring for a spouse with severe dementia, or being a refugee forced from one’s native country by war.

Distant stressors: traumatic experiences that occurred in the distant past yet can continue modifying the immune system because of their long-lasting emotional and cognitive consequences, such as child abuse, combat trauma or having been a prisoner of war. Much of their analysis goes on to review the similarities and differences among the 293 studies that they examined. These studies included a total of 18,941 subjects. “Stressful event sequences” appeared to be weakly associated with different immune consequences, depending on the type of event. There appeared to be different patterns for grief than for trauma, for example, but the associations weren’t strong enough for the authors to make new claims. They recommended further study.

The authors did find that the most chronic stressors - those which change people’s identities or social roles, are more beyond their control and seem endless - were associated with the most global suppression of immunity. In such situations almost all measures of immune function dropped across the board. The longer the stress, the more the immune system shifted from potentially adaptive changes (such as those in the acute “fight or flight” response) to potentially detrimental changes, at first in cellular immunity and then in broader immune function. This analysis suggests that stressors that turn a person’s world upside down and appear to offer no hope for the future probably have the greatest psychological and physiological impact.

The authors also found that age and disease status affected a person’s vulnerability to stress-related decreases in immune function. It seems that illness and age make it harder for the body to regulate itself.

This is a ground-breaking meta-analysis that helps us understand the complex relationship between stress and the immune system. It should lead to new treatments and to better stress management programs, especially for patients with HIV or other disorders that compromise immunity.

Reference: Segerstrom & Miller, 2004. Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry Psychological Bulletin, 130, 4.

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©2008 About.com, Inc., a part of The New York Times Company. All rights reserved.

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