Smoking is an established risk factor for
pancreatic cancer, previously investigated by the means of questionnaires. Using
cotinine as a
biomarker for tobacco exposure allows more accurate quantitative analyses to be performed. This study on
pancreatic cancer, nested within the European Prospective Investigation into
Cancer and Nutrition (EPIC cohort), included 146 cases and 146 matched controls. Using liquid chromatography-mass spectrometry, plasma
cotinine levels were analyzed on average 8.0 years before
cancer onset (5-95% range: 2.8-12.0 years). The relation between plasma
cotinine levels and
pancreatic cancer was analyzed with conditional logistic regression for different levels of
cotinine in a population of never and current smokers. This was also done for the self-reported number of smoked cigarettes per day at baseline. Every increase of 350 nmol/L of plasma
cotinine was found to significantly elevate risk of
pancreatic cancer [odds ratio (OR): 1.33, 95% confidence interval (CI): 1.11-1.60]. People with a
cotinine level over 1187.8 nmol/L, a level comparable to smoking 17 cigarettes per day, have an elevated risk of
pancreatic cancer, compared to people with
cotinine levels below 55 nmol/L (OR: 3.66, 95% CI: 1.44-9.26). The results for self-reported smoking at baseline also show an increased risk of
pancreatic cancer from cigarette smoking based on questionnaire information. People who
smoke more than 30 cigarettes per day showed the highest risk compared to never smokers (OR: 4.15, 95% CI: 1.02-16.42). This study is the first to show that plasma
cotinine levels are strongly related to
pancreatic cancer.