Table 2. Studies of possible correlation between vasectomy and prostate cancer.

	Study	Study design	Time range (year)	Total subjects/subjects with prostate cancer (n)	Relative risk (95% confidence interval)
Correlation found	Millard [42]	Review	1985–1996	14 reports	1.23 (1.01–1.49)
	Dennis et al [43]	Meta-analysis	1996–2001	24 reports	1.37 (1.15–1.62)
	Siddiqui et al [44]	Prospective cohort	1986–2010	49,405/6,023	Overall risk 1.10 (1.04–1.17)
					Risk of high-grade disease 1.22 (1.03–1.45)
					Risk of fatal disease 1.19 (1.00–1.43)
	Davenport et al [45]	Prospective cohort	1995–2011	111,914/13,885	1.05 (1.01–1.11)
	Husby et al [46]	Retrospective cohort	1977–2014	2,150,162/26,238	1.15 (1.10–1.20)
	Rohrmann et al [47]	Prospective cohort	1996–2004	3,373/78	Overall risk 2.03 (1.24–3.32)
					Risk of low-grade disease 2.87 (1.49–5.54)
	Seikkula et al [48]	Prospective cohort	1987–2014	38,124/413	1.15 (1.04–1.27)
No correlation found	Liu et al [49]	Prospective cohort	Before 2014	1,127,096/7,539	1.08 (0.87–1.34)
	Zhang et al [50]	Meta-analysis	1966–2013	331,436/1,245	1.07 (0.79–1.46)
	Jacobs et al [51]	Prospective cohort	1982–2012	363,726/7,451	1.01 (0.93–1.10)
	Nayan et al [52]	Matched cohort study	1994–2012	326,607/3,462	1.02 (0.95–1.09)
	Shang et al [53]	Meta-analysis	1980–2015	429,914/7,027	1.11 (0.98–1.27)
	Bhindi et al [54]	Systematic review	Before 2017	2,563,519/44,536	1.05 (1.02–1.09)
	Randall et al [55]	Systematic review	-	684,660/9,754	0.92 (0.70–1.21)
	Smith et al [56]	Prospective investigation	1992–2000	84,753/4,377	1.05 (0.96–1.15)
	DeAntoni et al [57]	Cross-sectional study	1993–1995	95,961/2,530	0.93 (0.77–1.14)
	Ferrís-I-Tortajada et al [58]	Retrospective study	1985–2010	42,425	1.1 (0.9–1.4)
	Bernal-Delgado et al [59]	Systematic review	1985–1996	14 reports	1.23 (1.01–1.49)
	Holt et al [60]	Retrospective study	2002–2005	1,001	1.0 (0.8–1.2)