Pancreatic cancer is an often-fatal disease that is hard to treat; it ranks fifth among the most common causes of cancer-related death in Europe and the United States. Smoking is known to increase the risk of pancreatic cancer, but until now there has been little evidence as to whether other lifestyle factors are implicated. However, findings appearing in a recent Journal of the American Medical Association now indicate that obesity and physical activity may also play a role.

A closer look

Harvard-affiliated investigators used information collected from more than 117,000 women participating in the Nurses' Health Study and 46,000 men participating in the Health Professionals Follow-Up Study, both long-term studies of United States population groups. Participants were followed for 20 years, during which 140 men and 210 women were diagnosed with pancreatic cancer. The researchers then analyzed the participants' physical activity levels and their body mass index (BMI), a measurement of body fatness, to look for an association between these two factors and the incidence of pancreatic cancer.

Link between weight and disease risk

After accounting for other known risk factors, men and women with a BMI of 30 or more (the definition for obesity) were 72% more likely to develop pancreatic cancer than participants whose BMI was at or below a healthy level of 23. A BMI of 30 is equivalent to a weight of 174 pounds (79 kg) for a 5'4" person (163 cm) or 209 pounds (95 kg) for someone who is 5'10" (178 cm).

Moderate physical activity, on the other hand, reduced the risk of pancreatic cancer. Men and women in the group that spent the most time walking or hiking - four or more hours a week - were only half as likely to develop pancreatic cancer compared with sedentary participants. Those individuals who spent as little as 1.5 hours a week walking or hiking were at slightly lower, but still substantially less risk.

More study is needed

The researchers are not certain what factors led to their findings. One possibility is that pancreatic cancer is linked to blood sugar and insulin abnormalities (the pancreas is the organ that produces insulin). Obesity has long been associated with problems such as insulin resistance and diabetes, while physical activity has been linked to improvements in blood sugar levels.

More research is called for before definitive conclusions can be drawn. Still, these results fall squarely in the realm of "can't hurt, might help." Obesity is associated with a host of potential medical problems, while study after study demonstrates benefits to engaging in moderate physical activity. A brisk half-hour to 45-minute walk on most days of the week might best be viewed as a very inexpensive form of health insurance.