Epidemiology
Walking or hiking < 20 min/wk was associated with twice the risk of pancreatic cancer when compared with > 4 hrs/wk in 164,000 men and women. Among non-overweight participants (BMI < 25 kg/m2) in this study, total physical activity was not related to the risk of pancreatic cancer. However, total physical activity was inversely associated with risk among overweight individuals.
The American Cancer Society estimates total pancreatic cancer cases and deaths in 2002 to be 30,300 and 29,700, respectively. Based on the information above, we estimate that the 30% of the U.S. population that undertakes 30 minutes of moderate physical activity each day is already preventing 2937 premature deaths and 2997 cases of pancreatic cancer each year. If the 70% of the sedentary population undertook walking 30 minutes or more each day for 5 or more days per week, then up to 6992 additional premature cases and 6854 premature deaths would be prevented. No known pharmaceutical approach achieves such potent prevention!
Biochemical/Cellular Mechanisms
Michaud et al speculated that their findings of physical inactivity's contribution to increased pancreatic cancer in subjects with BMI > 25 kg/m2 could be explained by high postprandial plasma glucose levels and hyperinsulinemia, ultimately resulting in increased free insulin-like growth factor-l (IGF-I). IGF-I has been shown to promote growth in human pancreatic cell lines. Currently, little information is available describing cellular mechanisms.
*2/282/5*
CANCER
