The association between coffee consumption and bladder cancer in the bladder cancer epidemiology and nutritional determinants (BLEND) international pooled study.

Inconsistent results for coffee consumption and bladder cancer (BC) risk have been shown in epidemiological studies. This research aims to increase the understanding of the association between coffee consumption and BC risk by bringing together worldwide case-control studies on this topic.

Data were collected from 13 case-control comprising of 5,911 cases and 16,172 controls. Pooled multivariate odds ratios (ORs), with corresponding 95% confidence intervals (CIs), were obtained using multilevel logistic regression models. Furthermore, linear dose-response relationships were examined using fractional polynomial models.

No association of BC risk was observed with coffee consumption among smokers. However, after adjustment for age, gender, and smoking, the risk was significantly increased for never smokers (ever vs. never coffee consumers: ORmodel2 1.30, 95% CI 1.06-1.59; heavy (> 4 cups/day) coffee consumers vs. never coffee consumers: ORmodel2 1.52, 95% CI 1.18-1.97, p trend = 0.23). In addition, dose-response analyses, in both the overall population and among never smokers, also showed a significant increased BC risk for coffee consumption of more than four cups per day. Among smokers, a significant increased BC risk was shown only after consumption of more than six cups per day.

This research suggests that positive associations between coffee consumption and BC among never smokers but not smokers.

Cancer causes & control : CCC. 2019 May 30 [Epub ahead of print]

Evan Yi-Wen Yu, Anke Wesselius, Frits van Osch, Mariana Carla Stern, Xuejuan Jiang, Eliane Kellen, Chih-Ming Lu, Hermann Pohlabeln, Gunnar Steineck, James Marshall, Mohamed Farouk Allam, Carlo La Vecchia, Kenneth C Johnson, Simone Benhamou, Zuo-Feng Zhang, Cristina Bosetti, Jack A Taylor, Maurice P Zeegers

NUTRIM School for Nutrition and Translational Research in Metabolism, University of Maastricht, Universiteitssingel 40 (Room C5.564), 6229 ER, Maastricht, The Netherlands. ., NUTRIM School for Nutrition and Translational Research in Metabolism, University of Maastricht, Universiteitssingel 40 (Room C5.564), 6229 ER, Maastricht, The Netherlands., Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA., Leuven University Centre for Cancer Prevention (LUCK), Louvain, Belgium., Department of Urology, Buddhist Dalin Tzu Chi General Hospital, Dalin Township, Chiayi County, Taiwan., Leibniz Institute for Prevention Research and Epidemiology-BIPS, Bremen, Germany., Clinical Cancer Epidemiology, Department of Oncology, Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden., Department of Cancer Prevention and Control, Roswell Park Cancer Institute, Buffalo, NY, USA., Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Section of Public Health and Human Sciences, University of Brescia, Brescia, Italy., Department of Clinical Medicine and Community Health, University of Milan, Milan, Italy., Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, ON, Canada., INSERM U946, Variabilite Genetique et Maladies Humaines, Fondation Jean Dausset/CEPH, Paris, France., Departments of Epidemiology, UCLA Center for Environmental Genomics, Fielding School of Public Health, University of California, Los Angeles (UCLA), Los Angeles, CA, USA., Laboratory of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri" IRCCS, Milan, Italy., Epidemiology Branch and Epigenetic and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, USA.