Fruit and Vegetable Intake and Risk of Pancreatic Cancer
Fruit and Vegetable Intake and Risk of Pancreatic Cancer
Fruit and vegetable intake may protect against pancreatic cancer, since fruits and vegetables are rich in potentially cancer-preventive nutrients. Most case-control studies have found inverse associations between fruit and vegetable intake and pancreatic cancer risk, although bias due to reporting error cannot be ruled out. In most prospective studies, inverse associations have been weaker and imprecise because of small numbers of cases. The authors examined fruit and vegetable intake in relation to pancreatic cancer risk in a pooled analysis of 14 prospective studies from North America, Europe, and Australia (study periods between 1980 and 2005). Relative risks and 2-sided 95% confidence intervals were estimated separately for the 14 studies using the Cox proportional hazards model and were then pooled using a random-effects model. Of 862,584 men and women followed for 7−20 years, 2,212 developed pancreatic cancer. The pooled multivariate relative risks of pancreatic cancer per 100-g/day increase in intake were 1.01 (95% confidence interval (CI): 0.99, 1.03) for total fruits and vegetables, 1.01 (95% CI: 0.99, 1.03) for total fruits, and 1.02 (95% CI: 0.99, 1.06) for total vegetables. Associations were similar for men and women separately and across studies. These results suggest that fruit and vegetable intake during adulthood is not associated with a reduced pancreatic cancer risk.
Worldwide, pancreatic cancer represents one of the most rapidly fatal of all cancers, with a 1-year case-fatality greater than 97%. Most pancreatic cancers are diagnosed at advanced stages, when tumor resection is not possible. Furthermore, current chemotherapy regimens have been unsuccessful at improving survival, and treatment is thus focused on palliation. Until feasible screening methods become available, prevention offers the most promising approach to reducing the morbidity and mortality associated with pancreatic cancer.
Few risk factors for pancreatic cancer are known. Tobacco smoking and obesity are modifiable factors with convincing evidence of increasing pancreatic cancer risk. Other factors that have been associated with increased risk include a family history of pancreatic cancer, chronic pancreatitis, type 2 diabetes, and some dietary factors, including alcohol consumption and a low intake of folate-containing foods.
Intake of fruits and vegetables may be protective for pancreatic cancer, since fruits and vegetables are rich in many potentially cancer-preventive agents. The risk of pancreatic cancer in relation to fruit and vegetable consumption has been examined in over 35 epidemiologic studies, and most have found inverse associations with fruit and/or vegetable intake. However, associations have been stronger in case-control studies than in cohort studies, and most case-control studies have relied on proxy respondents for exposure information, with proportions of proxies exceeding 50% of the case series in many studies. Thus, bias due to reporting error is difficult to rule out. In 2007, an international panel reviewed the majority of studies published through 2006 and concluded that there was limited evidence suggesting that fruit consumption reduces pancreatic cancer risk. The panel was unable to make a conclusion for vegetable consumption, because the available data were inconsistent.
In order to gain a better understanding of the relation of fruit and vegetable consumption to pancreatic cancer risk, we analyzed intakes of total and specific fruits and vegetables in the Pooling Project of Prospective Studies of Diet and Cancer (the Pooling Project), an international consortium of prospective cohort studies. Only 4; 2 studies were included in reference 8) of the 14 studies had previously published results on these relations. Using the primary data from these studies, we standardized the definitions of fruit and vegetable intake and covariate categories across studies and conducted multivariate analyses for the risk of pancreatic cancer overall and for particular population subgroups.
Abstract and Introduction
Abstract
Fruit and vegetable intake may protect against pancreatic cancer, since fruits and vegetables are rich in potentially cancer-preventive nutrients. Most case-control studies have found inverse associations between fruit and vegetable intake and pancreatic cancer risk, although bias due to reporting error cannot be ruled out. In most prospective studies, inverse associations have been weaker and imprecise because of small numbers of cases. The authors examined fruit and vegetable intake in relation to pancreatic cancer risk in a pooled analysis of 14 prospective studies from North America, Europe, and Australia (study periods between 1980 and 2005). Relative risks and 2-sided 95% confidence intervals were estimated separately for the 14 studies using the Cox proportional hazards model and were then pooled using a random-effects model. Of 862,584 men and women followed for 7−20 years, 2,212 developed pancreatic cancer. The pooled multivariate relative risks of pancreatic cancer per 100-g/day increase in intake were 1.01 (95% confidence interval (CI): 0.99, 1.03) for total fruits and vegetables, 1.01 (95% CI: 0.99, 1.03) for total fruits, and 1.02 (95% CI: 0.99, 1.06) for total vegetables. Associations were similar for men and women separately and across studies. These results suggest that fruit and vegetable intake during adulthood is not associated with a reduced pancreatic cancer risk.
Introduction
Worldwide, pancreatic cancer represents one of the most rapidly fatal of all cancers, with a 1-year case-fatality greater than 97%. Most pancreatic cancers are diagnosed at advanced stages, when tumor resection is not possible. Furthermore, current chemotherapy regimens have been unsuccessful at improving survival, and treatment is thus focused on palliation. Until feasible screening methods become available, prevention offers the most promising approach to reducing the morbidity and mortality associated with pancreatic cancer.
Few risk factors for pancreatic cancer are known. Tobacco smoking and obesity are modifiable factors with convincing evidence of increasing pancreatic cancer risk. Other factors that have been associated with increased risk include a family history of pancreatic cancer, chronic pancreatitis, type 2 diabetes, and some dietary factors, including alcohol consumption and a low intake of folate-containing foods.
Intake of fruits and vegetables may be protective for pancreatic cancer, since fruits and vegetables are rich in many potentially cancer-preventive agents. The risk of pancreatic cancer in relation to fruit and vegetable consumption has been examined in over 35 epidemiologic studies, and most have found inverse associations with fruit and/or vegetable intake. However, associations have been stronger in case-control studies than in cohort studies, and most case-control studies have relied on proxy respondents for exposure information, with proportions of proxies exceeding 50% of the case series in many studies. Thus, bias due to reporting error is difficult to rule out. In 2007, an international panel reviewed the majority of studies published through 2006 and concluded that there was limited evidence suggesting that fruit consumption reduces pancreatic cancer risk. The panel was unable to make a conclusion for vegetable consumption, because the available data were inconsistent.
In order to gain a better understanding of the relation of fruit and vegetable consumption to pancreatic cancer risk, we analyzed intakes of total and specific fruits and vegetables in the Pooling Project of Prospective Studies of Diet and Cancer (the Pooling Project), an international consortium of prospective cohort studies. Only 4; 2 studies were included in reference 8) of the 14 studies had previously published results on these relations. Using the primary data from these studies, we standardized the definitions of fruit and vegetable intake and covariate categories across studies and conducted multivariate analyses for the risk of pancreatic cancer overall and for particular population subgroups.
