Lifestyle Now May Affect Colon Cancer Survival Later

Previous smoking and obesity decreased colon cancer five year survival

(RxWiki News) Healthy diet and lifestyle choices reduce the risk for many diseases. What effect these pre-diagnosis choices have on survival after colon and rectal cancer has become clearer.

Recently, scientists looked at lifestyle factors to see if they affected survival after a cancer diagnosis. They looked at such factors as smoking, obesity, drinking and physical activity that existed before a diagnosis of colon and rectal cancer.

This research team found that colon and rectal cancer survivors who smoked, were obese or had other less healthy lifestyles were at an increased risk of dying in five years.

"Start healthy habits today to ensure your long-term health."

Colleen Pelser, PhD, from the Greenebaum Cancer Center at the University of Maryland in Baltimore, and a team of researchers conducted this study.

These researchers used data from the NIH-AARP Diet and Health Study. This study enrolled over 5,000 people aged 50 to 71 living in six states. Participants in the NIH-AARP study completed questionnaires at enrollment.

The surveys asked questions about diet, alcohol consumption, physical activity, body weight and smoking history.

Diet quality was scored by the research team on a scale from 0 to 100, based on the 2005 Dietary Guidelines for Americans.

A total lifestyle score was assigned to each participant’s answers. One point was given for having a normal body mass from 18.5 to less than 25 kg/m2, indicating the person was not overweight. One point was given for three or more episodes per week of physical activity, alcohol consumption of less than or equal to one drink per day for women and two drinks per day for men. One point also was given for not smoking, and another was given for diets that scored in the top two quality groups.

Total lifestyle scores ranged from 0 to 5, where 5 was the best score.

Cases of colon and rectal cancer were obtained by reviewing cancer registries in the different states. Deaths and causes of death were collected from the Social Security Administration Death Master File and the National Death Index.

The researchers identified 4,213 cases of colon cancer and 1,514 cases of rectal cancer among the study participants.

Of the colon cancer cases, 1,273 patients died during the five-year follow-up of the study — 856 from colorectal cancer (cancer that started either in the colon or rectum), 125 from other cancers, 108 from cardiovascular disease and 184 from other causes. 

In the cases of rectal cancer, 454 died within five years — 301 from colorectal cancer, 49 from other cancers, 43 from cardiovascular disease and 61 from other causes.

In this study of patients with colon and rectal cancer, pre-diagnosis smoking was associated with a 29 percent increase in death among those who smoked nine years ago or sooner compared to never smokers. The risk of dying from cardiovascular disease in these smokers was increased 88 percent compared to nonsmokers.

For current smokers, the risk of death from any cause was 74 percent higher and risk of death from colorectal cancer was 46 percent higher compared to nonsmokers’ risks.

Obese people, those with a BMI of 30 or over,  had a 19 percent increased risk of death and an 84 percent increased risk of dying from cardiovascular disease compared to people of normal weight.

Lower rates of death from cardiovascular disease were associated with better diet scores and alcohol consumption.

Patients with colon and rectal cancer who had higher total lifestyle scores had lower rates of death from all causes.

Dr. Pelser and colleagues noted several limitations of their study.  Lifestyle information was only collected at the beginning of the study, before cancer diagnosis, so lifestyle changes made after diagnosis were not considered in the study. Additionally, different lengths of time passed between the lifestyle questionnaire and the cancer diagnosis.

The authors remarked that several of the factors that they found to be associated with increased mortality were modifiable lifestyle factors.

“Our study adds to a growing body of literature demonstrating the importance of maintaining a healthy lifestyle before cancer diagnosis,” these authors wrote.

This research appeared in the March issue of Cancer.

Grants from the Intramural Research Program of the National Cancer Institute provided funding for the study.

The authors did not disclose any conflicts of interest.

Review Date: 
March 12, 2014