Context Diabetes mellitus and elevated postload plasma glucose levels have
been associated with an increased risk of pancreatic cancer in previous stu
dies. By virtue of their influence on insulin resistance, obesity and physi
cal inactivity may increase risk of pancreatic cancer.
Objective To examine obesity, height, and physical activity in relation to
pancreatic cancer risk.
Design and Setting Two US cohort studies conducted by mailed questionnaire,
the Health Professionals Follow-Up Study (initiated in 1986) and the Nurse
s' Health Study (initiated in 1976), with 10 to 20 years of follow-up.
Participants A total of 46648 men aged 40 to 75 years and 117041 women aged
30 to 55 years who were free of prior cancer at baseline and had complete
data on height and weight.
Main Outcome Measures Relative risk of pancreatic cancer, analyzed by self-
reported body mass index (BMI), height, and level of physical activity.
Results During follow-up, we documented 350 incident pancreatic cancer case
s. Individuals with a BMI of at least 30 kg/m(2) had an elevated risk of pa
ncreatic cancer compared with those with a BMI of less than 23 kg/m(2) (mul
tivariable relative risk [RR], 1.72; 95% confidence interval [CI], 1.19-2.4
8), Height was associated with an increased pancreatic cancer risk (multiva
riable RR, 1.81; 95% CI, 1.31-2.52 for the highest vs lowest categories). A
n inverse relation was observed for moderate activity (multivariable RR, 0.
45; 95% CI, 0.29-0.70 for the highest vs lowest categories; P for trend <.0
01). Total physical activity was not associated with risk among individuals
with a BMI of less than 25 kg/m(2) but was inversely associated with risk
among individuals with a BMI of at least 25 kg/m(2) (pooled multivariable R
R, 0.59; 95% CI, 0.37-0.94 for the top vs bottom tertiles of total physical
activity; P for trend=.04).
Conclusion In 2 prospective cohort studies, obesity significantly increased
the risk of pancreatic cancer. Physical activity appears to decrease the r
isk of pancreatic cancer, especially among those who are overweight.