Table 1. Main characteristics of studies included in this meta-analysis.

Author, year	Country	No. of cases	No. of cohort	Age	Study name or source	Duration of follow-up	Quality score	Adjustment factors
Kelly et al., 2017 [7]	USA	7,822	69,873	62 (55-74)	PLCO Cancer Screening Trial	13 y	7	Age, trial arm, screening center, race, education, married or cohabiting, diabetes, smoking, PSA history, family history of prostate cancer, and myocardial infarction
Bonn et al., 2016 [8]	Sweden	735	15,827	65.2 (SD 10.1)	STHLM-2 cohort	3.5 y	6	Age, physical activity, education, smoking, stress, family history of prostate cancer
Grotta et al., 2015 [10]	Sweden	904	13,109	55.1 (SD 15.2)	Swedish National March Cohort	13 y	7	Age, physical activity, education, smoking, alcohol, and diabetes
Møller et al., 2015 [9]	Denmark	1,813	26,877	50-64	Diet, Cancer and Health Study	15.5 y	7	Age
Rundle et al., 2013 [11]	USA	494	6,692	65.85	Henry Ford Health System	1990–2007	7	Age, race, follow-up duration, biopsy versus TURP, date of procedure, PSA levels, family history of PCa, the number of PSA tests and DRE
Bassett et al., 2012 [12]	Australia	1,374	16,514	68 (47-86)	Melbourne Collaborative Cohort Study	15 y	8	Age, country of birth, and education
Discacciati et al., 2011 [14]	Sweden	2,084	36,959	45-79	Central Sweden	1998–2008	7	Age, energy intake, physical activity, education, smoking, family history of PCa, personal history of diabetes, and BMI at age 30 years
Stocks et al., 2010 [23]	Sweden	10,002	336,159	34.7 ± 13.1	Swedish Construction Workers cohort	22.2 y	6	Age, birth year, smoking, and blood pressure
Wallström et al., 2009 [24]	Sweden	817	10,564	45-73	Malmo Diet and Cancer Study	11 y	7	Age, height, co-habitation status, socioeconomic status, alcohol, smoking, prevalent diabetes, physical activity, birth country, and total intake of EPA, DHA, red meat, and calcium
Pischon et al., 2008 [20]	Eight European countries	2,446	129,502	52.8 (25-70)	European Prospective Investigation into Cancer and Nutrition	8.5 y	8	Age, study center, education, smoking, alcohol, physical activity, and height
Littman et al., 2007 [19]	USA	832	34,754	50-76	Vitamins and Lifestyle Study	2000–2004	6	Age, family history of PCa, race, and PSA screening in the 2 years before baseline
Rodriguez et al., 2007 [4]	USA	5,252	69,991	50-74	Cancer Prevention Study II	1992–2003	8	Age, race, education, family history of PCa, total calorie intake, smoking, history of PSA testing, history of diabetes, and physical activity
Wright et al., 2007 [25]	USA	9,986	287,760	50–71	NIH-AARP Diet and Health Study	5 y	6	Age, race, smoking, education, personal history of diabetes, and family history of PCa
Gong et al., 2006 [5]	USA	1,936	10,258	≥ 55	Prostate Cancer Prevention Trial	7 y	7	Age, race, treatment, diabetes, and family history of PCa
Kurahashi et al., 2006 [17]	Japan	311	49,850	40-69	Japan Public Health Centre-based Prospective Study	1990–2003	7	Age, area, smoking, family history of PCa, and marital status
Habel et al., 2000 [16]	USA	2,079	70,712	18-84	Kaiser Permanente Medical Care Program	19.5 y	7	Age, race, and birth year
Putnam et al., 2000 [21]	USA	101	1,572	68.1 (40-86)	A Cohort of Iowa Men	1986–1995	6	Age, total energy, carbohydrates, linoleic acid, lycopene, retinol, red meat, and family history of PCa
Schuurman et al., 2000 [22]	Netherland	681	58,279	55-69	Netherlands Cohort Study	6.3 y	6	Age, family history of PCa, and socioeconomic status
Cerhan et al., 1997 [13]	USA	71	1,050	65-101	Iowa 65+ Rural Health Study	1982–1993	5	Age, smoking, and physical activity
Giovannucci et al., 1997 [15]	USA	1,369	47,781	40-75	Health Professionals Follow-Up Study	1986–1994	5	Age, height, and BMI at age 21
Le Marchand et al., 1994 [18]	USA	198	20,316	≥ 18	Hawaii	1975–1989	7	Age, ethnicity, and income

BMI, body mass index; No., number; y, years; PCa, prostate cancer; NA, not available; PLCO, Prostate, Lung, Colorectal and Ovarian.