title: Ejaculatory frequency and the risk of aggressive prostate cancer: Findings from a case-control study.
abstract: Recent literature reports inverse associations with ejaculator frequency and prostate cancer (PC). We sought to explore the relationship between ejaculatory frequency from ages 20 to 50 and subsequent development of aggressive PC.
  
  
  
  We conducted a case-control study sampling 2,141 men from private urology practices in Victoria, Australia. Cases were defined as men with high grade or high stage PC and controls being biopsy negative men. Ejaculation frequency recalled at age decades 20, 30, and 40 second was assessed by questionnaire. Unconditional multivariable logistic regression models were used to generate odds ratios (ORs).
  
  
  
  An inverse association with ejaculatory frequency at age 30 to 39 was observed (OR per 5-unit increase per week = 0.83, 95% CI: 0.72-0.96) but not at ages 20 to 29 (OR = 1.01, 95% CI: 0.89-1.14) or ages 40 to 49 (OR = 0.95, 95% CI: 0.81-1.12). This result differed between men with new sexual partners after age 30 (OR = 0.77, P = 0.009) and those with no new partners (OR = 0.97, P = 0.8) though the test for a difference between these estimates was not significant (P = 0.11).
  
  
  
  We found only weak evidence of an inverse association between ejaculatory frequency in the fourth decade of life and advanced PC, which was not significantly modified by number of new sexual partners. No relationship was found for ejaculatory frequency in the third and fifth decades of life.
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia; Department of Urology, Austin Health, Heidelberg, Australia. Electronic address: nathan.p.papa@gmail.com.
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Papa
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: MacInnis
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia.
authors.forename: Dallas R
authors.initials: DR
authors.lastname: English
authors.affiliation: Department of Urology, Austin Health, Heidelberg, Australia.
authors.forename: Damien
authors.initials: D
authors.lastname: Bolton
authors.affiliation: Monash University Eastern Health Clinical School, Box Hill, Australia; Eastern Health, Box Hill, Australia.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Davis
authors.affiliation: Department of Urology, Austin Health, Heidelberg, Australia; Olivia Newton-John Cancer Research Institute, Melbourne, Australia; Department of Surgical Oncology, Peter MacCallum Cancer Institute, Melbourne, Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Lawrentschuk
authors.affiliation: Alfred Health Radiation Oncology, The Alfred Hospital, Prahran, Australia.
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: Millar
authors.affiliation: TissuPath, Melbourne, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Pedersen
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Severi
authors.affiliation: Department of Pathology, Genetic Epidemiology Laboratory, The University of Melbourne, Melbourne, Australia.
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Southey
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia.
authors.forename: John L
authors.initials: JL
authors.lastname: Hopper
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia.
authors.forename: Graham G
authors.initials: GG
authors.lastname: Giles
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004542:Ejaculation; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011471:Prostatic Neoplasms / Q000453:epidemiology*; D012747:Sexual Partners; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Case-control; Ejaculation; Epidemiology; Prostate; Prostate cancer