Colorectal Cancer Survivors Ask: What Can I Do Now?

Colorectal cancer is the second leading cause of cancer-related deaths in the U.S. In recent years treatment has improved outcomes and new research suggests that Lifestyle risk factors are associated with the development of colorectal cancer and survival following treatment for colorectal cancer.  Exercise, physical inactivity, weight management, smoking, heavy alcohol consumption, a diet high in red or processed meats, and a diet inadequate in fruits and vegetables all can contribute to worse survivorship following treatment for colorectal cancer. Importantly they can all be changed!

Benefits of Exercise

Clinical trials have evaluated the benefit of exercise in cancer patients, and most have found an association with improved quality of life, reduced risk of cancer recurrence and prolonged survival.

In a meta-analysis of 49,000 survivors of colorectal cancer (CRC) physical activity had a dose-related effect on survival. A reduction in mortality risk was observed with increasing exercise and physical activity.Similarly, a 16-year longitudinal study found that more physical activity before and after a diagnosis of CRC was associated with lower mortality, whereas more sedentary time was associated with a higher risk.4

Nutrition & Weight Management

Maintaining a healthy body weight and specific nutritional factors have also been found to reduce the risk of developing colon cancer and delaying its recurrence.

The National Surgical and Adjuvant Bowel Project evaluated the association between Body Mass Index (BMI) and outcomes in two clinical trials of adjuvant chemotherapy involving 4,288 individuals with colon cancer.  When compared with normal-weight people (BMI, 18.5-24.9 kg/m2), very obese patients (BMI =35 kg/m2) had a 38% greater risk for colon cancer recurrence or development of a second primary cancer, a 36% increased risk for CRC-related mortality, and a 28% increased risk for death from any cause.9

In addition to obesity, certain diets appear to contribute to poor survivorship following treatment for colon cancer.  In a study involving 1,000 patients with stage II/III colon cancer patients in the highest quintile of a Western diet (red meat, fat, refined foods, desserts) versus lowest had double or triple the risk for CRC recurrence and CRC-related death. Patients whose diets reflected a high glycemic index also had worse disease-free survival, recurrence-free survival and overall survival.10

Consumption of "Red Meat" and processed meat has been shown to increase the risk of cancers of the distal colon and the rectum, whereas milk and calcium consumption have shown a protective effect against left-sided tumors in which the rise in incidence was most prominent. It is plausible that unfavorable dietary patterns in children and young adults over the past three decades may have contributed to the increase in colorectal cancer among young adults observed in the study.

Red meat and processed meats were specifically investigated in the American Cancer Society’s Cancer Prevention Study II Nutrition Cohort , which examined the diets of 2,315 people diagnosed with CRC, 1,186 of whom were followed up to 16 years. A consistently high intake of red meat (highest vs. lowest quartile), both before and after a diagnosis of CRC, raised the relative risk for death from CRC to 1.79.11

The NCCN dietary recommendations include high intake of vegetables, fruits, grains, fish and poultry, and a limit on the bad things, including red meat, processed foods and sugars.

Fruit and Vegetable Intake

To evaluate the link between fruit and vegetable intake and colorectal polyps, researchers affiliated with the Nurses’ Health Study evaluated the link between diet and polyps among more than 34,000 women who had undergone a colonoscopy or sigmoidoscopy between 1980 and 1998. The study suggested that a diet high in fruit may reduce the risk of developing colorectal polyps:3

  • Compared to women who ate one or fewer servings of fruit per day, women who ate five or more servings of fruit per day were 40% less likely to develop colorectal polyps.
  • There was little evidence that high vegetable intake reduced the risk of colorectal polyps.

Another study suggests that regular exercise and a diet that includes fish may help colon cancer patients improve their odds of avoiding a cancer recurrence. The likelihood that patients will suffer a return of colon cancer more than doubles if they eat fish less than twice a week, or if they get less than 60 minutes of moderate exercise a week.14

The multinational study involved 1,515 colon cancer patients from the United States, Poland, Vietnam and Western Europe, including 188 people who suffered a recurrence of their cancer following initial treatment. Researchers carefully surveyed the patients, asking about their diet, exercise, and lifestyle and whether they smoked or consumed alcohol.

The investigators found that individuals who eat fish less than twice a week or exercise for less than an hour each week are about 2.5 times more likely to have a recurrence of their colon cancer. The doctors were unable to identify any other dietary factors that affect the risk of colon cancer recurrence, including intake of red meat, alcohol consumption, or smoking.

Researchers have hypothesized that the omega-3 fatty acids in fish might somehow reduce colon cancer risk. The findings in the current study regarding fish and exercise are consistent with earlier studies that investigated what might increase someone’s risk of developing colon cancer in the first place.

The potential benefits of exercise are increasingly appreciated; exercise reduces inflammation in the body and helps thwart obesity, which are two other risk factors for colon cancer. Exercise also reduces insulin levels in the body, and insulin is a growth factor for both normal cells and malignant cells.

What About Fiber?

Dietary fiber (found in cereals, fruits, and vegetables) could potentially reduce the risk of colorectal cancer though a variety of mechanisms: Fiber could dilute cancer-causing agents that pass through the colon and rectum in the feces; it could speed stool passage through the colon and rectum, minimizing exposure to cancer-causing agents; and it could reduce exposure to bile acids.

While high fiber intake has been hypothesized to reduce the risk of colorectal cancer studies have produced mixed results. In a large pooled analysis of 13 studies, published in the Journal of the American Medical Association (JAMA), researchers found that dietary fiber was not associated with a reduced risk of colorectal cancer.12

Harvard University researchers studied 88,757 women, evaluating the correlation between their diet and the development of colorectal cancer. After a followup period of 16 years, the researchers found that a high-fiber diet does not lower the incidence of colorectal cancer. There was no evidence to suggest that increasing the dietary intake of total, cereal, fruit, or vegetable fiber is associated with a reduction in risk for colorectal adenomatous polyps or colorectal cancer.

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These researchers concluded that there are many health reasons to eat a diet high in fiber, particularly to help reduce the risk for coronary artery disease; however, such a diet does not appear to help prevent the development of colorectal polyps or colorectal cancer.13

Aspirin

Several research studies suggest that taking an aspirin a day can reduce the risk of developing adenomas of the colon, colon cancer and colon cancer recurrence.

Alcohol and Tobacco Use

The adverse health effects of alcohol and tobacco use are well documented for a number of health conditions and over consumption may also influence both the development and recurrence of CRC. 

In a clinical study researchers assessed information from more than 160,000 colorectal cancer patients. Alcohol and tobacco use were classified as current, past, or never.1

  • Current use of alcohol or tobacco was linked with a younger age at colorectal cancer diagnosis.
  • Among those who were current users of both alcohol and tobacco, the average age at colorectal cancer diagnosis was 63 years. This was almost eight years younger than the average age at colorectal cancer diagnosis among individuals who never smoked or drank.5

Long-term smoking significantly increases the risk of colorectal cancer, according to a study by American Cancer Society researchers that was published in the Journal of the National Cancer Institute.In an effort to determine a relationship between smoking and colorectal cancer, the ACS researchers examined 14 years of data (1982-1996) collected from the Cancer Prevention Study II (CPS II). They evaluated the smoking patterns of 312,332 men and 469,019 women as reported by these participants when they entered the study in 1982. The researchers found that colorectal cancer death rates were highest among current smokers, intermediate among former smokers and lowest among never smokers. The risk of dying from colorectal cancer was higher among those who smoked for 20 or more years.

The duration and amount of smoking was a significant factor, as the data showed that the risk of colorectal cancer increased with the number of cigarettes smoked daily and the number of years of smoking. A younger age at initiation also increased the risk. On the other hand, the colorectal cancer risk decreased with each year after quitting smoking. The data also showed that cigar and pipe smokers had an increased risk of colorectal cancer as well.

Since the data showed that the risk of dying from colorectal cancer increased with the duration and amount of smoking, the researchers concluded that there might be a causal relationship between smoking and colorectal cancer. If this causal relationship does indeed exist, then approximately 12% of colorectal cancer deaths in the U.S. are attributable to smoking.

Although more research is necessary to determine the relationship between smoking and colorectal cancer the results of this study indicate that current and former smokers may want to consider more frequent screening tests for colorectal cancer. People concerned with screening for this disease or who may be interested in smoking cessation programs can consult with their physicians for more information. 

Heart Disease and Diabetes Increase Risk of Colorectal Cancer

Individuals who are diabetic or those with coronary artery disease have an increased risk of developing colorectal cancer.6

Screening for colorectal cancer is recommended beginning at the age of 50, or earlier for those with a family history of the disease. Research continues to evaluate possible variables that may influence the risk of developing colorectal cancer. Individuals at a higher risk may benefit from more frequent screening so that their disease may be detected in its earliest stages.

Researchers from Washington University in St. Louis recently conducted a clinical study to evaluate the rates of colorectal cancer in women with diabetes.This study included 100 women with diabetes and 500 women who did not have diabetes.

  • 37% of women with diabetes had an adenoma, versus 24% for those who were not diabetic.
  • 14% of women with diabetes had advanced adenomas, compared with 6% of women without diabetes.
  • At 42%, obese women with diabetes had the highest incidence of adenomas, and non-obese, non-diabetic women had the lowest rate of adenomas (23%).

Researchers from the University of Hong Kong also conducted a study to evaluate the risk of heart disease on the development of adenomas of the colon.7 This study included 307 patients; nearly half of the patients (46.3%) had coronary artery disease.

Colorectal cancer was diagnosed in 30.3% of patients with heart disease, compared with 19.4% of patients without heart disease, and 16.9% of patients with heart disease had advanced colorectal cancer, compared with only 6.7% of patients without heart disease.

Researchers from both of these trials have stressed that colorectal cancer is increased in patients with diabetes and heart disease. They recommend screening for these groups of patients. Patients with diabetes or heart disease may wish to speak with their physician regarding their individual risks and benefits of undergoing screening for colorectal cancer.

References:

  1. Zisman AL, Nickolov A, Brand RE et al. Associations Between Age at Diagnosis and Location of Colorectal Cancer and the Use of Alcohol and Tobacco. Archives of Internal Medicine. 2006;166:629-634.
  2. Michels KB, Giovannucci E, Chan AT, et al. Fruit and vegetable consumption and colorectal adenomas in the Nurses’ Health Study. Cancer Research. 2006;66:3942-3953.
  3. Ann Oncol 2014;25[7]:1293-1311.
  4. J Clin Oncol 2013;31[7]:876-885.
  5. Zisman AL, Nickolov A, Brand RE et al. Associations Between Age at Diagnosis and Location of Colorectal Cancer and the Use of Alcohol and Tobacco. Archives of Internal Medicine. 2006;166:629-634.
  6. Elwing J, et al .Type 2 Diabetes Mellitus: The Impact on Colorectal Adenoma Risk in Women. Proceedings from the Digestive Disease Week meeting. May 2006. Abstract 1245.

  7. Chan A, et al. Patients with coronary artery disease are at high risk for developing colorectal cancer and adenoma: an interim analysis of a prospective study. Proceedings from the Digestive Disease Week meeting. May 2006. Abstract 208.

  8. Journal of the National Cancer Institute, Vol 92, No 23, 2000

  9. J Natl Cancer Inst 2006;98[22]:1647-1654.

  10. J Natl Cancer Inst 2012;104[22]:1702-1711.

  11. J Clin Oncol 2013;31[22]:2773-2782.

  12. Park Y, Hunter DJ, Spiegelman D et al. Dietary Fiber Intake and Risk of Colorectal Cancer: A Pooled Analysis of Prospective Cohort Studies. JAMA. 2005;294:2849-2857.

  13. New England Journal of Medicine, Vol 340, No 3, pp 169-176, 1999.

  14. Mohammed Shaik, M.D., fellow, Michigan State University’s Breslin Cancer Center; Smitha Krishnamurthi, M.D., ASCO spokeswoman, oncologist and associate professor, Case Western Reserve University School of Medicine, Cleveland, Ohio; presentation, American Society of Clinical Oncology meeting, Chicago, May 14, 2014.