Diabetes Mellitus, Obesity, and Risk of Pancreatic Ductal Adenocarcinoma: a Large Case-Control Study from Iran.

BACKGROUND Pancreatic cancer (PC) is a deadly, globally increasing cancer. The causes of PC are still insufficiently known, however smoking, diabetes mellitus (DM), and obesity have been identified as risk factors of PC, mostly in the developed countries. We evaluated these risk factors and their contribution to PC among an Iranian population. METHODS Cases and controls were selected from patients who were registered to a tertiary gastrointestinal diseases referral hospital in Tehran, Iran, from Jan 2012 to Jan 2018. Information on risk factors was collected by personal interview using a structured questionnaire. Logistic regression models were used to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs). RESULTS We recruited 470 new patients with histopathological PC diagnosis and 526 sex and age-matched controls. Cigarette-smoking [AOR: 1.65 (1.15-2.38)], opium use [AOR: 1.58 (1.06-2.35)], DM [AOR: 1.99 (1.31-3.02)], and having a history of any cancer in a first-degree family member [AOR: 1.53 (1.14-2.05)] were associated with an increased risk of PC. We did not find an association between obesity [AOR: 0.99 (0.71-1.38)] and PC. Approximately 4.6%, 5.9%, 8.2%, and 10.9% risk of PC were related to cigarette-smoking, opium use, DM, and family history of any cancer, respectively. CONCLUSION This study supports that DM is associated with PC risk; however, similar to many studies in Asia, obesity is not associated with PC in Iranians. DM has the highest impact on PC development in Iranian women.