Can physical activity modulate pancreatic cancer risk? a systematic review and meta‐analysis

Abstract

Numerous epidemiological studies have examined the association between physical activity and pancreatic cancer; however, findings from individual cohorts have largely not corroborated a protective effect. Among other plausible mechanisms, physical activity may reduce abdominal fat depots inducing metabolic improvements in glucose tolerance and insulin sensitivity, thereby potentially attenuating pancreatic cancer risk. We performed a systematic review to examine associations between physical activity and pancreatic cancer. Six electronic databases were searched from their inception through July 2009, including MEDLINE and EMBASE, seeking observational studies examining any physical activity measure with pancreatic cancer incidence/mortality as an outcome. A random effects model was used to pool individual effect estimates evaluating highest vs. lowest categories of activity. Twenty-eight studies were included. Pooled estimates indicated a reduction in pancreatic cancer risk with higher levels of total (five prospective studies, RR: 0.72, 95% CI: 0.52-0.99) and occupational activity (four prospective studies, RR: 0.75, 95% CI: 0.59-0.96). Nonsignificant inverse associations were seen between risks and recreational and transport physical activity. When examining exercise intensity, moderate activity appeared more protective (RR: 0.79, 95% CI: 0.52-1.20) than vigorous activity (RR: 0.97, 95% CI: 0.85-1.11), but results were not statistically significant and the former activity variable incorporated marked heterogeneity. Despite indications of an inverse relationship with higher levels of work and total activity, there was little evidence of such associations with recreational and other activity exposures.Pancreas cancer is the thirteenth most common malignancy in Europe but is the fifth most frequent cause of cancer death. 1 Although relatively rare it grows aggressively, it metastasises early and is often detected late; consequently, 5 year survival is formidably low at only 5% in Europe and 75% of patients die within a year of their initial diagnosis. 2 Current pharmacological and radiological modalities confer little benefit to this neoplasm; a focus on methods for both its prevention and earlier detection are therefore pivotal. Despite this dismal prognosis, the etiology of pancreatic cancer remains poorly understood. Cigarette smoking is the most strongly associated risk factor for this disease; a meta-analysis of 82 articles (42 retrospective and 40 prospective studies) has shown that smoking may increase the risk of this neoplasm by as much as 75% (RR: 1.74, 95% CI: 1.61-1.87). 3 In addition, long-standing type II diabetes 4,5 and obesity 6-8 have also been associated with this multifaceted disease. Despite the potential for physical activity to ameliorate the effect of these latter risk factors, findings from observational epidemiological studies examining physical activity and pancreatic cancer risk remain ambiguous. 9,10 Physical inactivity and obesity, particularly abdominal adiposity, increase the risk ...

Is physical activity a protective factor against pancreatic cancer?

“…According to the Second Expert Report published by the World Cancer Research Fund in 2007, excess body weight increases the risk for developing pancreatic cancer and, therefore, the risk may be decreased by maintaining the weight. Although the results are not consistent, some studies showed an inverse association between physical activity and pancreatic cancer (19,20). Physical activity has been proved to have benefi cial effects on metabolic processes as it decreases glucose levels, increases utilization of glucose in the organism, affects lipid profi le, positively infl uences blood pressure and reduces the amount of body fat.…”

The Association between Leisure Time Physical Activity and Pancreatic Cancer Risk in Adults: A Systematic Review and Meta-analysis

“…Controls who choose to participate in research studies tend to be more healthy, have a different distribution of LTPA and, therefore, may cause an overinflation in the risk estimate. This meta-analysis was strengthened by the large number of studies included, allowing for extensive subgroup analysis to characterize various subgroups of interest and examine potential (19,20,26). Furthermore, from a methodologic perspective, many studies do not include any or adequate measures of occupational, household-and transportation-related activity, therefore, there is an increased potential for publication bias or gaps in this literature when examining total physical activity in comparison to LTPA.…”

“…The body of literature examining the association between physical activity and other cancer sites, including pancreatic cancer (15,18), continues to expand. Previous metaanalyses by Bao and colleagues (19) and O'Rorke and colleagues (20) suggested a possible protective effect of occupational physical activity on pancreatic cancer incidence [relative risk (RR), 0.75; 95% confidence interval (CI), 0.58-0.96 and RR, 0.75; 95% CI, 0.59-0.96, respectively]. However, they reported lack of evidence to support leisure time physical activity (LTPA) in pancreatic cancer risk reduction.…”

Statins and pancreatic cancer

“…Notably, circulating levels of adiponectin, an adipocyte-secreted hormone with insulin sensitizing and anti-inflammatory properties, has been revealed to be inversely correlated with pancreatic cancer risk, independent of other risk factors (25). Notably, meta-analyses of other anthropometric measures such as physical activity have primarily produced non-significant findings in relation to protective effects against pancreatic cancer (26)(27)(28) (28).…”