Background To evaluate the individual and combined effects of enterolactone, vitamin D, free testosterone, Chlamydia trachomatis and HPV-18 on the risk of prostate cancer in a large population-based biochemical material that combined three Nordic serum sample banks.
Material and methods A joint cohort of 209 000 healthy men was followed using cancer registry linkages. From this cohort altogether 699 incident cases of prostate cancer were identified. Four controls were selected by incidence density sampling and matching for country, age and date of the blood sampling. Complete data for all investigated exposures was available for 483 eligible cases and 1055 eligible controls. Multivariate regression analyses were performed to investigate the solitary and combined effects. Results The solitary effects were small. Significantly increased risk [rate ratio 1. 6 (95% CI 1. 0-2. 5)] was found in those seronegative for C. trachomatis infection. The joint effect in risk levels of enterolactone and vitamin D was antagonistic [observed rate ratio (RR) 1. 4 (1. 0-2. 1), expected RR 2. 0 (1. 0-4. 1)] as well as that of HPV-18 and C. trachomatis [observed RR 1. 9 (0. 8-4. 5), expected RR 9. 9 (1. 1-87. 0)]. Conclusion A large follow-up study combining data from several previously investigated exposures to investigate joint effects found no evidence that exposure to two risk factors would increase the risk of prostate cancer from that expected on basis of exposure to one risk factor. If anything, the results were consistent with antagonistic interactions.
Acta oncologica (Stockholm, Sweden). 2016 Feb 15 [Epub ahead of print]
Sonja Lumme, Leena Tenkanen, Hilde Langseth, Randi Gislefoss, Matti Hakama, Pär Stattin, Göran Hallmans, Herman Adlercreutz, Pekka Saikku, Ulf-Håkan Stenman, Pentti Tuohimaa, Tapio Luostarinen, Joakim Dillner
a National Institute for Health and Welfare (THL) , Helsinki , Finland ;, b Helsinki Heart Study , Helsinki , Finland ;, c Cancer Registry of Norway , Cancer Registry of Norway, Institute of Population-based Research, Department of Research , Oslo, Norway ;, c Cancer Registry of Norway , Cancer Registry of Norway, Institute of Population-based Research, Department of Research , Oslo, Norway ;, d University of Tampere , Tampere , Finland ;, f Department of Surgical and Perioperative Sciences, Urology and Andrology , Umeå University , Umeå , Sweden ;, g Department of Biobank Research , Umeå University , Umeå , Sweden ;, h Phytoestrogen Analyses, Division of Clinical Chemistry , University of Helsinki , Helsinki , Finland ;, i Department of Medical Microbiology , University of Oulu , Oulu , Finland ;, j Clinical Chemistry and Haematology , University of Helsinki , Helsinki , Finland ;, k School of Medicine , University of Tampere , Tampere , Finland ;, e Finnish Cancer Registry , Institute for Statistical and Epidemiological Cancer Research , Helsinki , Finland ;, l Department of Laboratory Medicine , Karolinska Institutet , Stockholm , Sweden.