A prospective study of physical activity and the risk of pancreatic cancer among women (United States)

Abstract

Background: Several epidemiologic studies have examined the association between physical activity and pancreatic cancer risk; however, the results of these studies are not consistent.

Methods: This study examined the associations of total, moderate, and vigorous physical activity to pancreatic cancer in a cohort of 33,530 U.S. women enrolled in the Breast Cancer Detection Demonstration Project (BCDDP). At baseline (1987-1989), information on physical activity over the past year was obtained using a self-administered questionnaire. Cox proportional hazards regression was used to estimate relative risks (RR) and 95% confidence intervals of pancreatic cancer risk.

Results: 70 incident cases of pancreatic cancer were ascertained during 284,639 person years of follow-up between 1987-1989 and 1995-1998. After adjustment for age, body mass index, smoking status, history of diabetes, and height, increased physical activity was related to a suggestively decreased risk of pancreatic cancer. The RRs for increasing quartiles of total physical activity were 1.0, 0.80, 0.66, 0.52 (95% CI = 0.26, 1.05; ptrend = 0.05). This association was consistent across subgroups defined by body mass index and smoking status. We also observed statistically non-significant reductions in pancreatic cancer risk for women in the highest quartile of moderate (RR = 0.57; 95% CI = 0.26, 1.26) and highest quartile of vigorous physical activity (RR = 0.63; 95% CI = 0.31, 1.28) compared to their least active counterparts.

Conclusion: Our study provides evidence for a role of physical activity in protecting against pancreatic cancer.

Figure 1

Participant Flow in the BCDDP Follow-Up Study: (A) Inclusion criteria for the analytic cohort and (B) Timeline of follow-up for participants in the analytic cohort. ¹From the original screening population, the BCDDP follow-up cohort included all 4,275 women diagnosed with breast cancer, all 25,114 women with biopsies indicating benign breast disease, all 9,628 women who were recommended for breast biopsy or surgery but did not undergo either procedure, and 25,165 participants (who neither underwent nor were recommended for breast biopsy) matched to women with breast cancer or positive biopsies for breast cancer on age, time of entry into the screening program, length of cohort participation, ethnicity, and location. ² We excluded 5,691 subjects with a cancer (other than non-melanoma skin cancer) diagnosed prior to the 1987 questionnaire, 10 women who were lost to follow-up, 4,218 women with a missing or extreme body mass index (greater than 3 standard deviations above or below the mean), and 8,242 women with inadequate physical activity information.