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

Abstract

Background: To evaluate the dose-response relationship between cigarette smoking and pancreatic cancer and to examine the effects of temporal variables.

Methods: 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.

Results: 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.

Conclusions: 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.

Figure 1

Cumulative meta-analysis of pancreatic cancer risk in current cigarette smokers as compared with never smokers. International Pancreatic Cancer Case–Control Consortium (PanC4). OR, odds ratio; 95% CI, 95% confidence intervals. ^aIncluding the unpublished Louisiana State University study.

Figure 2

Study-specific and pooled odds ratios (ORs)^a for pancreatic cancer according to ever cigarette smokers as compared with never smokers. International Pancreatic Cancer Case–Control Consortium (PanC4). ^aStudy-specific ORs were adjusted for age, sex, race/ethnicity, education, body mass index, history of diabetes, history of pancreatitis, alcohol drinking, and study center for multicentric studies. Pooled ORs were computed using random-effects models. Ca, cases; CI, confidence intervals; Co, controls; LSU, Louisiana State University; MSKCC, Memorial Sloan–Kettering Cancer Center; NCI, National Cancer Institute; SEARCH, Surveillance of Environmental Aspects Related to Cancer in Humans; UCSF, University of California, San Francisco.

Figure 3

Study-specific and pooled odds ratios (ORs)^a for pancreatic cancer according to level of cigarette smoking in current smokers as compared with never smokers. (A) <15 cigarettes per day, (B) 15–24 cigarettes per day, (C) ≥15 cigarettes per day. International Pancreatic Cancer Case–Control Consortium (PanC4). ^aStudy-specific ORs were adjusted for age, sex, race/ethnicity, education, body mass index, history of diabetes, history of pancreatitis, alcohol drinking, and study center for multicentric studies. Pooled ORs were computed using random-effects models. Ca, cases; CI, confidence intervals; Co, controls; LSU, Louisiana State University; MSKCC, Memorial Sloan–Kettering Cancer Center; NCI, National Cancer Institute; SEARCH, Surveillance of Environmental Aspects Related to Cancer in Humans; UCSF, University of California, San Francisco.