Recently, a consensus statement by a panel of experts concluded that people with type 2 diabetes have an increased risk of several types of cancer. Now, an AICR research paper highlights the key role of lifestyle factors in helping patients with pre-diabetes and type 2 diabetes lower their cancer risk.
AICR’s InDepth, released this August, and the consensus statement, published in the June issue of CA: A Cancer Journal for Clinicians, both found the strongest evidence linking type 2 diabetes to cancers of the liver, pancreas and endometrium. People with diabetes were approximately twice as likely to get one of these cancers, according to the consensus report. Evidence was weaker but still clear – approximately 20 percent to 50 percent higher – for cancers of the colon/rectum, post-menopausal breast and bladder.
Paradoxically, evidence suggests that men with diabetes have a lower risk of prostate cancer, but further research is needed.
“The consensus statement laid the groundwork showing the link is there and weighed the issue from the medical standpoint,” said Karen Collins, MS, RD, Nutrition Advisor for AICR and author of the InDepth report. “This clear link between type 2 diabetes and cancer risk makes the message of lifestyle change for patients and health professionals much more important.”
In the United States, diabetes affects nearly 24 million people – almost 8 percent of the population – according to the Centers for Disease Control and Prevention (CDC). Another 57 million people are estimated to have pre-diabetes, a condition that puts people at increased risk for diabetes.
“It’s pretty clear now that at least for many cancers it’s not necessarily the diabetes associated with increased risk, but the whole metabolic environment . . .”
Type 2 diabetes and cancer share many risk factors, including obesity, poor diet, physical inactivity and aging. Possible mechanisms linking the two diseases include hyperinsulinemia, hyperglycemia and inflammation. Many of these conditions relate to metabolic syndrome, a cluster of disorders that increases the risk of diabetes and heart disease, and possibly cancer.
“It’s pretty clear now that at least for many cancers it’s not necessarily the diabetes associated with increased risk, but the whole metabolic environment associated with diabetes, such as inflammation, high levels of insulin and insulin-like growth factors,” said Collins. These conditions are also present in people with pre-diabetes.
At one time, health professionals treated people with diabetes by focusing on controlling blood sugar. Yet diabetes is a known risk factor for heart disease, and blood sugar control does not sufficiently decrease risk of cardiovascular disease. Now, the evidence pointing to an increased cancer risk heightens the importance of emphasizing a healthy lifestyle pattern to patients.
“We know that adding more and more medication to control blood sugar will not solve the underlying metabolic problem, which means it may not prevent the long-term complications of cancer and heart disease,” said Collins.
For the most part, lifestyle recommendations for diabetes, heart disease and cancer are similar – a healthy diet, regular physical activity and maintaining a healthy weight – but some points are tweaked. For example, a person with diabetes might be most concerned about total carbohydrates. Moderate alcohol intake may lower risk of diabetes, yet it increases the risk of some cancers.
The recent research also shows there is a limited window of opportunity before damage may accumulate, says Collins, which adds an urgency to lifestyle change for patients with pre-diabetes and diabetes.
Excerpted from ScienceNow. The co-chair of the diabetes and cancer consensus report, Harvard School of Public Health Professor Edward Giovannucci, MD, SCD, will be speaking at AICR’s upcoming research conference on October 21-22.
The high cost of obesity applies to far more than health, with the financial price adding up to thousands of dollars every year, according to a report released last month. The report estimated the annual cost of obesity at $4,879 for women and $2,646 men. When the value of years lost to premature death was included, costs increased to $8,365 a year for obese women and $6,518 a year for obese men.
The report, by the George Washington University School of Public Health and Health Services, included cost measures related to medical care, absenteeism from work, short-term disability, and insurance. The findings also highlighted the disparity in costs between obese men and women for job-related costs.
The more a woman sits, regardless of activity level, the greater her risk of endometrial cancer, finds a new study that adds to the growing research on the health risks of sedentary behavior. The study, published in the British Journal of Cancer, also confirmed AICR’s expert report finding that regular physical activity reduces the risk of endometrial cancer.
In the study, the authors analyzed all relevant population studies published through 2009, separating activity by recreational and occupational. For both categories of activity, the women who were most active had almost a 30 percent lower risk of endometrial cancer compared to the least active women.
When the authors analyzed sedentary behavior, they found that women who were both inactive and who sat for nine or more hours per day had twice the risk of endometrial cancer as active women who sat fewer than three hours per day. Independent of activity level and after adjusting for obesity, the finding still held that women who sat for over nine hours per day had a higher risk of endometrial cancer compared to those who sat fewer than three hours daily.
Higher levels of the mineral selenium may protect both men and women against bladder cancer, although the degree may vary by gender, suggests an analysis of studies published in the September issue of Cancer Epidemiology, Biomarkers & Prevention. Plants absorb selenium from the soil, and people take in selenium from eating plant foods and animals that eat selenium.
For the analysis, the authors analyzed data on the topic published before March 2010, ending up with seven studies. The studies measured selenium in participants’ blood and toenails and examined the risk of developing bladder cancer. Participants included individuals mostly from the United States, but also from Belgium, Finland and the Netherlands.
The researchers noted a protective effect of selenium, mainly among women, which they believe may result from gender-specific differences in the mineral's accumulation and excretion in women. Yet large observational studies or randomized trials are needed, conclude the authors, before suggesting selenium supplementation to bladder cancer patients.
The health effects of a low-carbohydrate diet may depend upon whether the rest of the diet comes from animals or vegetables, suggests a new study published in the Annals of Internal Medicine. The study found that a low-carbohydrate diet higher in animal-based foods compared to vegetable-based is linked to a higher risk of mortality from all causes and cancer, specifically. In contrast, low-carbohydrate diets higher in plant-based foods were linked to lower risk of mortality from all causes and cardiovascular disease.
The researchers evaluated data from two prospective studies that tracked women for 26 years and men for 20 years. Together, the studies included data from approximately 130,000 participants without heart disease, diabetes, or cancer at the start of the study. Diets were determined as animal-based or vegetable-based depending upon the reported amounts of animal or vegetable sources of fat and protein.
Overall, dieters who followed the strictest low-carbohydrate diets had a 12 percent higher death rate than those who ate the least low-carbohydrate diets. After separating the low-carbohydrate diets into animal-based and vegetable-based, the risks of death veered higher or lower during the course of the study, depending upon whether participants took in most of their protein and fats from animal or vegetable sources. For example, those on a low-carbohydrate diet who consumed the highest amounts of animal foods had a 28 percent increased risk of cancer-related death compared to those who ate the least amounts from animal sources; low-carbohydrate dieters who had the highest amount of vegetable sources had a 20 percent decreased risk of all-cause mortality.