International Pancreatic Cancer Case-Control Consortium Research Articles

Tobacco, alcohol and pancreatic disease: key findings from global consortia

(RR) were 1.74 (95% confidence interval, CI, 1.39-2.13) for current and 1.32 (95% CI 1.03-1.71) for former smokers [2, 3]. Chronic pancreatitis is associated to heavy alcohol drinking, though the risk estimates remain open to discussion. Epidemiological data are limited, but consistent with clinical ones to indicate that (heavy) drinking is related to chronic pancreatitis [2]. There is consistent evidence that tobacco is also a major factor for chronic pancreatitis. With reference to tobacco, the RRs from a meta-analysis were 2.8 (95% CI 1.7-4.8) for current and 1.4 (95% CI 1.1-1.9) for former smokers and these associations were not totally accounted for by heavy alcohol drinking [4]. Tobacco is responsible for 10 to 20% of all chronic pancreatitis. In non-alcoholic idiopathic chronic pancreatitis, smoking is associated with disease progression [5]. Cigarette smoking is the major risk factor for pancreatic cancer. In the Pancreatic Cancer Consortium (PanScan; 1481 cases, 1539 controls) the pooled RR was 1.77 (95% CI 1.38-2.26) for current and 1.09 (95% CI 0.91-1.30) for former smokers [6]. In the International Pancreatic Cancer Case-Control Consortium (PanC4; 6507 cases, 12,890 controls), the RR was 2.20 (95% CI 1.71-2.83) for current smokers and rose to 3.39 (95% CI 2.36-1.86) for heavy smokers; the RR was 1.17 (95% CI 1.02-2.83) for former smokers [7]. Cigar smoking was also associated with pancreatic cancer (RR 1.62, 95% CI 1.15-2.29), whereas no consistent association was found for smokeless tobacco, nor for pipe smoking [8]. A meta-analysis of 21 case-control and 11 cohort studies provided conclusive evidence that moderate drinking was unrelated to pancreatic cancer, but heavy drinking (3 or more drinks/day) gave a RR of 1.22 (95% CI 1.12-1.34) [9]. In the PanScan collaborative re-analysis of cohort studies (1530 cases, 1520 controls), there was no overall association with total alcohol intake, but the RR was 1.38 (95% CI 0.9-2.3) for drinking ≥60g day and rose to 2.23 (95% CI 1.0-4.9) for male heavy liquors drinkers [10]. In a pooled analysis of 14 cohort studies (2187 cases) the RR for >30g day was 1.22 (95% CI 1.031.45) [11]. In the PanC4 study (5585 cases, 11,822 controls), the RR was 1.46 (95% CI 1.16-1.83) for ≥6 drinks day; no association was observed with moderate drinking [12]. Possible mechanisms of action of alcohol include acetaldehyde, fatty acid ethyl esters, free radicals, DNA damage and inflammation [12]. Possible mechanisms of action of smoking include tobacco specific nitrosamines (NKK), polycyclic aromatic hydrocarbons (PAH) and other smoking-associated chemicals, and smoking as an inflammatory agent and a progressor in carcinogenesis [7].

Gallbladder disease, cholecystectomy, and pancreatic cancer risk in the International Pancreatic Cancer Case-Control Consortium (PanC4).

The association among gallbladder disease, cholecystectomy, and pancreatic cancer is unclear. Moreover, time interval between gallbladder disease or cholecystectomy and pancreatic cancer diagnosis is not considered in most previous studies. To quantify the association among gallbladder disease, cholecystectomy, and pancreatic cancer, considering time since first diagnosis of gallbladder disease or cholecystectomy. We used data from nine case-control studies within the Pancreatic Cancer Case-Control Consortium, including 5760 cases of adenocarcinoma of the exocrine pancreas and 8437 controls. We estimated pooled odds ratios and the corresponding 95% confidence intervals by estimating study-specific odds ratios through multivariable unconditional logistic regression models, and then pooling the obtained estimates using fixed-effects models. Compared with patients with no history of gallbladder disease, the pooled odds ratio of pancreatic cancer was 1.69 (95% confidence interval, 1.51-1.88) for patients reporting a history of gallbladder disease. The odds ratio was 4.90 (95% confidence interval, 3.45-6.97) for gallbladder disease diagnosed <2 years before pancreatic cancer diagnosis and 1.11 (95% confidence interval, 0.96-1.29) when ≥2 years elapsed. The pooled odds ratio was 1.64 (95% confidence interval, 1.43-1.89) for patients who underwent cholecystectomy, as compared to those without cholecystectomy. The odds ratio was 7.00 (95% confidence interval, 4.13-11.86) for a surgery <2 years before pancreatic cancer diagnosis and 1.28 (95% confidence interval, 1.08-1.53) for a surgery ≥2 years before. There appears to be no long-term effect of gallbladder disease on pancreatic cancer risk, and at most a modest one for cholecystectomy. The strong short-term association can be explained by diagnostic bias and reverse causation.

Dietary acrylamide and the risk of pancreatic cancer in the International Pancreatic Cancer Case–Control Consortium (PanC4)

Occupational exposure to acrylamide was associated with excess mortality from pancreatic cancer, though in the absence of dose-risk relationship. Few epidemiological studies have examined the association between acrylamide from diet and pancreatic cancer risk. We considered this issue in a combined set of 1975 cases of pancreatic cancer and 4239 controls enrolled in six studies of the Pancreatic Cancer Case-Control Consortium (PanC4). We calculated pooled odds ratios (ORs) and their 95% confidence intervals (CI) by estimating study-specific ORs through multivariate unconditional logistic regression models and pooling the obtained estimates using random-effects models. Compared with the lowest level of estimated dietary acrylamide intake, the pooled ORs were 0.97 (95% CI, 0.79-1.19) for the second, 0.91 (95% CI, 0.71-1.16) for the third, and 0.92 (95% CI, 0.66-1.28) for the fourth (highest) quartile of intake. For an increase of 10µg/day of acrylamide intake, the pooled OR was 0.96 (95% CI, 0.87-1.06), with heterogeneity between estimates (I2 = 67%). Results were similar across various subgroups, and were confirmed when using a one-stage modelling approach. This PanC4 pooled-analysis found no association between dietary acrylamide and pancreatic cancer.

Menstrual and Reproductive Factors, Hormone Use, and Risk of Pancreatic Cancer: Analysis From the International Pancreatic Cancer Case-Control Consortium (PanC4).

We aimed to evaluate the relation between menstrual and reproductive factors, exogenous hormones, and risk of pancreatic cancer (PC). Eleven case-control studies within the International Pancreatic Cancer Case-control Consortium took part in the present study, including in total 2838 case and 4748 control women. Pooled estimates of odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated using a 2-step logistic regression model and adjusting for relevant covariates. An inverse OR was observed in women who reported having had hysterectomy (ORyesvs.no, 0.78; 95% CI, 0.67-0.91), remaining significant in postmenopausal women and never-smoking women, adjusted for potential PC confounders. A mutually adjusted model with the joint effect for hormone replacement therapy (HRT) and hysterectomy showed significant inverse associations with PC in women who reported having had hysterectomy with HRT use (OR, 0.64; 95% CI, 0.48-0.84). Our large pooled analysis suggests that women who have had a hysterectomy may have reduced risk of PC. However, we cannot rule out that the reduced risk could be due to factors or indications for having had a hysterectomy. Further investigation of risk according to HRT use and reason for hysterectomy may be necessary.

Vitamin D and pancreatic cancer: a pooled analysis from the Pancreatic Cancer Case–Control Consortium

The potential role of vitamin D in the aetiology of pancreatic cancer is unclear, with recent studies suggesting both positive and negative associations. We used data from nine case-control studies from the International Pancreatic Cancer Case-Control Consortium (PanC4) to examine associations between pancreatic cancer risk and dietary vitamin D intake. Study-specific odds ratios (ORs) were estimated using multivariable logistic regression, and ORs were then pooled using a random-effects model. From a subset of four studies, we also calculated pooled estimates of association for supplementary and total vitamin D intake. Risk of pancreatic cancer increased with dietary intake of vitamin D [per 100 international units (IU)/day: OR = 1.13, 95% confidence interval (CI) 1.07-1.19, P = 7.4 × 10(-6), P-heterogeneity = 0.52; ≥230 versus <110 IU/day: OR = 1.31, 95% CI 1.10-1.55, P = 2.4 × 10(-3), P-heterogeneity = 0.81], with the association possibly stronger in people with low retinol/vitamin A intake. Increased risk of pancreatic cancer was observed with higher levels of dietary vitamin D intake. Additional studies are required to determine whether or not our finding has a causal basis.

Diabetes, antidiabetic medications, and pancreatic cancer risk: an analysis from the International Pancreatic Cancer Case-Control Consortium

Type 2 diabetes mellitus has been associated with an excess risk of pancreatic cancer, but the magnitude of the risk and the time-risk relationship are unclear, and there is limited information on the role of antidiabetic medications. We analyzed individual-level data from 15 case-control studies within the Pancreatic Cancer Case-Control Consortium, including 8305 cases and 13 987 controls. Pooled odds ratios (ORs) were estimated from multiple logistic regression models, adjusted for relevant covariates. Overall, 1155 (15%) cases and 1087 (8%) controls reported a diagnosis of diabetes 2 or more years before cancer diagnosis (or interview, for controls), corresponding to an OR of 1.90 (95% confidence interval, CI, 1.72-2.09). Consistent risk estimates were observed across strata of selected covariates, including body mass index and tobacco smoking. Pancreatic cancer risk decreased with duration of diabetes, but a significant excess risk was still evident 20 or more years after diabetes diagnosis (OR 1.30, 95% CI 1.03-1.63). Among diabetics, long duration of oral antidiabetic use was associated with a decreased pancreatic cancer risk (OR 0.31, 95% CI 0.14-0.69, for ≥15 years). Conversely, insulin use was associated with a pancreatic cancer risk in the short term (OR 5.60, 95% CI 3.75-8.35, for <5 years), but not for longer duration of use (OR 0.95, 95% CI 0.53-1.70, for ≥15 years). This study provides the most definitive quantification to date of an excess risk of pancreatic cancer among diabetics. It also shows that a 30% excess risk persists for more than two decades after diabetes diagnosis, thus supporting a causal role of diabetes in pancreatic cancer. Oral antidiabetics may decrease the risk of pancreatic cancer, whereas insulin showed an inconsistent duration-risk relationship.

Ulcer, gastric surgery and pancreatic cancer risk: an analysis from the International Pancreatic Cancer Case–Control Consortium (PanC4)

BackgroundPeptic ulcer and its treatments have been associated to pancreatic cancer risk, although the evidence is inconsistent. MethodsWe pooled 10 case–control studies within the Pancreatic Cancer Case–control Consortium (PanC4), including 4717 pancreatic cancer cases and 9374 controls, and estimated summary odds ratios (OR) using multivariable logistic regression models. ResultsThe OR for pancreatic cancer was 1.10 [95% confidence interval (CI) 0.98–1.23] for history of ulcer (OR = 1.08 for gastric and 0.97 for duodenal ulcer). The association was stronger for a diagnosis within 2 years before cancer diagnosis (OR = 2.43 for peptic, 1.75 for gastric, and 1.98 for duodenal ulcer). The OR was 1.53 (95% CI 1.15–2.03) for history of gastrectomy; however, the excess risk was limited to a gastrectomy within 2 years before cancer diagnosis (OR = 6.18, 95% CI 1.82–20.96), while no significant increased risk was observed for longer time since gastrectomy. No associations were observed for pharmacological treatments for ulcer, such as antacids, H2-receptor antagonists, or proton-pump inhibitors. ConclusionsThis uniquely large collaborative study does not support the hypothesis that peptic ulcer and its treatment materially affect pancreatic cancer risk. The increased risk for short-term history of ulcer and gastrectomy suggests that any such association is due to increased cancer surveillance.

Pancreatitis and pancreatic cancer risk: a pooled analysis in the International Pancreatic Cancer Case-Control Consortium (PanC4)

Pancreatitis is a known risk factor for pancreatic cancer; however, an unknown fraction of the disease is thought to be a consequence of tumor-related duct obstruction. A pooled analysis of a history of pancreatitis and risk of pancreatic cancer was carried out considering the time interval between diagnoses and potential modification by covariates. Adjusted pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated from 10 case-control studies (5048 cases of ductal pancreatic adenocarcinoma and 10,947 controls) taking part in the International Pancreatic Cancer Case-Control Consortium (PanC4). The association between pancreatitis and pancreatic cancer was nearly three-fold at intervals of >2 years between diagnoses (OR: 2.71, 95% CI: 1.96-3.74) and much stronger at intervals of ≤2 years (OR: 13.56, 95% CI: 8.72-21.90) probably reflecting a combination of reverse causation and antecedent misdiagnosis of pancreas cancer as pancreatitis. The younger (<65 years) pancreatic cancer cases showed stronger associations with previous (>2 years) pancreatitis (OR: 3.91, 95% CI: 2.53-6.04) than the older (≥65 years) cases (OR: 1.68, 95% CI: 1.02-2.76; P value for interaction: 0.006). Despite a moderately strong association between pancreatitis (diagnosed before >2 years) and pancreatic cancer, the population attributable fraction was estimated at 1.34% (95% CI: 0.612-2.07%), suggesting that a relatively small proportion of pancreatic cancer might be avoided if pancreatitis could be prevented.

Cigarette smoking and pancreatic cancer: an analysis from the International Pancreatic Cancer Case-Control Consortium (Panc4)

To evaluate the dose-response relationship between cigarette smoking and pancreatic cancer and to examine the effects of temporal variables. We analyzed data from 12 case-control studies within the International Pancreatic Cancer Case-Control Consortium (PanC4), including 6507 pancreatic cases and 12 890 controls. We estimated summary odds ratios (ORs) by pooling study-specific ORs using random-effects models. Compared with never smokers, the OR was 1.2 (95% confidence interval [CI] 1.0-1.3) for former smokers and 2.2 (95% CI 1.7-2.8) for current cigarette smokers, with a significant increasing trend in risk with increasing number of cigarettes among current smokers (OR=3.4 for ≥35 cigarettes per day, P for trend<0.0001). Risk increased in relation to duration of cigarette smoking up to 40 years of smoking (OR=2.4). No trend in risk was observed for age at starting cigarette smoking, whereas risk decreased with increasing time since cigarette cessation, the OR being 0.98 after 20 years. This uniquely large pooled analysis confirms that current cigarette smoking is associated with a twofold increased risk of pancreatic cancer and that the risk increases with the number of cigarettes smoked and duration of smoking. Risk of pancreatic cancer reaches the level of never smokers ∼20 years after quitting.

Alcohol consumption and pancreatic cancer: a pooled analysis in the International Pancreatic Cancer Case–Control Consortium (PanC4)

Heavy alcohol drinking has been related to pancreatic cancer, but the issue is still unsolved. To evaluate the role of alcohol consumption in relation to pancreatic cancer, we conducted a pooled analysis of 10 case-control studies (5585 cases and 11,827 controls) participating in the International Pancreatic Cancer Case-Control Consortium. We computed pooled odds ratios (ORs) by estimating study-specific ORs adjusted for selected covariates and pooling them using random effects models. Compared with abstainers and occasional drinkers (< 1 drink per day), we observed no association for light-to-moderate alcohol consumption (≤ 4 drinks per day) and pancreatic cancer risk; however, associations were above unity for higher consumption levels (OR = 1.6, 95% confidence interval 1.2-2.2 for subjects drinking ≥ 9 drinks per day). Results did not change substantially when we evaluated associations by tobacco smoking status, or when we excluded participants who reported a history of pancreatitis, or participants whose data were based upon proxy responses. Further, no notable differences in pooled risk estimates emerged across strata of sex, age, race, study type, and study area. This collaborative-pooled analysis provides additional evidence for a positive association between heavy alcohol consumption and the risk of pancreatic cancer.

Cigar and pipe smoking, smokeless tobacco use and pancreatic cancer: an analysis from the International Pancreatic Cancer Case-Control Consortium (PanC4)

BackgroundCigarette smoking is the best-characterized risk factor for pancreatic cancer. However, data are limited for other tobacco smoking products and smokeless tobacco. Materials and methodsWe conducted a pooled analysis of cigar and pipe smoking and smokeless tobacco use and risk of pancreatic cancer using data from 11 case–control studies (6056 cases and 11338 controls) within the International Pancreatic Cancer Case-Control Consortium (PanC4). Pooled odds ratios (OR) and the corresponding 95% confidence intervals (CI) were estimated by unconditional multiple logistic regression models adjusted for study center and selected covariates. ResultsCompared with never tobacco users, the OR for cigar-only smokers was 1.6 (95% CI: 1.2–2.3), i.e. comparable to that of cigarette-only smokers (OR 1.5; 95% CI 1.4–1.6). The OR was 1.1 (95% CI 0.69–1.6) for pipe-only smokers. There was some evidence of increasing risk with increasing amount of cigar smoked per day (OR 1.82 for ≥ 10 grams of tobacco), although not with duration. The OR for ever smokeless tobacco users as compared with never tobacco users was 0.98 (95% CI 0.75–1.3). ConclusionThis collaborative analysis provides evidence that cigar smoking is associated with an excess risk of pancreatic cancer, while no significant association emerged for pipe smoking and smokeless tobacco use.