Health Briefs

Dr_Robert_WascherAugust 2 , 2002

by Robert A. Wascher, M.D., F.A.C.S.

Mammography Saves Lives!
The controversy surrounding a mammography study, published in Lancet last year by Danish researchers, would appear to be quashed by a new study published in the current issue of the journal Cancer.  In the Lancet study, a statistical review of previous Swedish studies showing a reduction in death rates with routine screening mammography concluded that these prior studies were flawed, and that there was no evidence that mammography saved lives.  Subsequent critiques of the Lancet paper have largely eviscerated that conclusion, but patients and doctors around the world were left stunned and uncertain about the implications of this controversy.  The current study in Cancer looked at breast cancer-related death rates in women aged 40 to 69 years, comparing women who received routine screening mammograms with women who did not.  The study evaluated nearly one-third of all Swedish women, and detected the occurrence of 14,092 cases of breast cancer, and 2,044 deaths due to breast cancer, among the women studied.   After more than 10 years of follow-up, the researchers found that routine screening mammography reduced the risk of dying from breast cancer by about 44%.  This finding is consistent with the observations of cancer physicians over the past 20 years, as routine screening mammography has become been widely implemented throughout most developed nations, including the United States.  It has long been known that breast cancer survival rates correspond to the extent of disease, or stage, with an excellent survival rate present for women with small primary tumors and no evidence of cancer spread outside of the breast.  Most of the previous studies that have failed to find a survival benefit associated with mammography followed study volunteers for only 5-10 years

Compared to many other cancers, breast cancer is often a relatively slow-growing cancer, and the relatively long natural course of the disease requires at least 10 years of study prior to drawing any firm conclusions.  This new study in Cancer highlights this fact by showing progressively increasing survival benefits from screening mammography beyond 10 years of observation.  This study, as well as other studies published this spring, convincingly show that mammography saves lives, and probably by diagnosing breast cancers when they are still very small and confined to the breast.  While 10-15% of breast cancers do not show up on mammograms, mammography is still the single most sensitive and accurate screening tool available for the early detection of breast cancer.  All women should generally begin screening mammography at 40 years of age.

Obesity & the Risk of Heart Failure
Approximately 8% of Americans are thought to be morbidly obese (weight 100 lbs greater than ideal body weight), while about 55% of the population is overweight (Body Mass Index, or BMI, 25.0-29.9) or obese (BMI >30).  Morbid obesity is associated with a greatly elevated risk of heart failure, high blood pressure, diabetes, blood clots, lung disease and other life-threatening maladies.  Heart failure occurs when the heart’s pumping chambers can no longer pump enough blood to meet the body’s needs.  According to the National Heart, Lung, and Blood Institute, 5 million Americans have chronic heart failure, and half of these people will succumb to their disease within 5 years.  The incidence and death rate due to heart failure is increasing.  Each year, 400,000 new cases are diagnosed, and the number of annual deaths due to this condition have more than quadrupled over the past 30 years.

A new study, appearing in this week’s New England Journal of Medicine, looks at the effects of excess weight and obesity on the incidence of congestive heart failure.  Specifically, the study looked at rather moderate degrees of obesity among nearly 6,000 participants in the ongoing Framingham Heart Study.  The BMI of study volunteers was calculated (BMI = weight in kilograms divided by the square of the height in meters), and the incidence of heart failure was noted during the average 14 years of study follow-up.  Causes of heart failure unrelated to obesity were considered and corrected for in reaching the study’s conclusions.  For every BMI incremental increase of 1 unit, there was a 5% increase in the risk of heart failure among men, and a 7% increase among women.  When compared with people who had a normal BMI (<25), obese volunteers had a doubling of the risk of heart failure. 

This study is yet another warning sign that the epidemic of excessive weight and obesity in our country is a dangerous development in terms of individual and public health.  Moreover, this is the first study to conclusively demonstrate that even relatively modest levels of excessive weight are associated with significant increases in the risk of potentially life-threatening heart disease.  Rather than suing McDonalds or Burger King for the unhealthy nutritional content of some of their menu items, maintaining a healthy low fat diet and a regular exercise schedule would appear to be a more effective strategy to maintain good health.

High Sugar Diets & the Risk of Colon Cancer
In the current issue of Cancer Research is a study that looks at the effects of high sugar diets and the risk of colon cancer.  There have been previous research studies that have linked high concentrations of dietary sugar with precancerous changes in the lining of the colon and in the liver, although such findings have been rather inconclusive to date.  In this study, laboratory rats were fed diets containing various levels of sugar.  The study identified an increasing incidence of a mutation associated with colon cancer in the lining of the rats’ colon with increasing levels of dietary sugar.  No cancer-associated changes in the liver were identified with respect to dietary sugar levels, however.  The study appears to show that, at least in rats, table sugar (sucrose) can directly or indirectly cause DNA mutations that have previously been associated with the development of colon cancer. 

So, in addition to staying on a low fat diet to protect your heart and other vital organs, you might also want to watch the amount of sugar in your diet.  In addition to possible adverse effects on the colon, high levels of sugar in the diet are associated with an increased risk of diabetes, obesity and reduced lifespan.

Abuse During Childhood & Possible Effects of Genes on Antisocial Behaviors
This week’s issue of the journal Science reports that a variant of a gene in the brain that produces the enzyme monoamine oxidase A (MAOA) may play a role in the development of antisocial behavior.  The study looked at a large cohort of male children who had been abused or otherwise maltreated during childhood.  The study volunteers were observed from childhood through adulthood for signs of antisocial behaviors.  The authors found that a variant of the MAOA gene that causes increased levels of this enzyme in the brain was, in fact, associated with a significantly lower incidence of aggressive—and other antisocial—behaviors.  MAOA breaks down several neurotransmitters in the brain, and MAOA inhibitors were once the most commonly used class of drugs used to treat depression before seretonin reuptake inhibitors (e.g., Prozac) came along. 

This study suggests that genetic traits can potentially modify a person’s response to certain environmental conditions, and to an abusive environment during childhood in particular.  It also suggests potential therapeutic strategies for at least some cases of abuse-related antisocial behavior.  This, of course, raises complex social and ethical issues, but such issues are bound to arise more frequently as additional discoveries linking human biology and behavior occur.

Dr. Robert A. Wascher

Dr. Robert A. Wascher is a senior research fellow in molecular & surgical oncology at the John Wayne Cancer Institute in Santa Monica, CA
Site Meter