Table 4.

Characteristics of studies included in the meta-analysis

Author, yr (Ref)	Country	Study design	PCOS diagnostic criteria	Cancer diagnostic criteria	PCOS group characteristics	Control group characteristics	Outcome of interest	Adjustments	Unadjusted OR (95% CI)	Quality assessment
Ding et al. , 2018 (11)	Taiwan	Cohort	ICD-9-CM1 Code 256.4	ICD-9-CM Code 174 and 175	N = 8155 Age = 27.7 (7.0) BMI = Not reported	N = 32620 Age = 27.5 (7.9) BMI = Not reported	Endometrial, ovarian, and breast cancer	Age, comorbidities	Endometrial cancer OR: 14.685 (4.096, 52.650) ovarian cancer OR:1.60 (0.62, 4.13) breast cancer OR:0.80 (0.47, 1.35)	High
Harris et al. , 2017 (27)	US	Case-control	Not reported	Not reported	N = 78 Age and BMI not reported for case	N = 4063 Age and BMI not reported for control	Ovarian cancer	Age, study, parity, oral contraceptive use, center, tubal ligation, family history of ovarian cancer	1.16 (0.74, 1.82)	High
Kim et al. , 2016 (16)	US	Case-control	Rotterdam criteria	Not reported	N = 67 Age = 53.8 $\pm$ 12.2 BMI = 27.4 $\pm$ 6.2	N = 2951 Age = 58.0 $\pm$ 12.8 BMI = 26.5 $\pm$ 5.7	Breast cancer	Age, physical activity	1.30 (0.80, 2.12)	High
Shen et al. , 2015 (15)	Taiwan	Cohort	NIH4 or ICD-9-CM	ICD-9-CM Code 174	N = 3566 Age = 27.04 (22.66-32.10) BMI = Not reported	N = 14264 Age = 27.05 (22.72-32.10) BMI = Not reported	Endometrial, ovarian, and breast cancer	Age, hypertension, diabetes mellitus, dyslipidemia, coronary artery disease, congestive heart disease, cerebrovascular disease, chronic pulmonary disease, urbanization, and income	Endometrial cancer OR: 10.013 (1.942, 51.629) ovarian cancer OR: 0.89 (0.19, 4.12) breast cancer OR: 1.87 (0.99, 3.53)	High
Ghasemi et al. , 2012 (29)	Iran	Case-control	Rotterdam	Histologically confirmed	N = 27 Age = 30-51 BMI not reported	N = 305 Age = 30-51 BMI not reported	Breast cancer	None	0.67 (0.30, 1.48)	Moderate
Bodmer et al. , 2011 (33)	UK	Case-control	Used diagnosis from GPRD	Based on evidence of cancer-related therapy	N = 28 Age = 61.2 $\pm$ 13.1	N = 10753 Age = 61.2 $\pm$ 13.1	Ovarian cancer	BMI, smoking, prior, use of hormones, history o hysterectomy, endometriosis	1.55 (0.63, 3.84)	Moderate
Fearnley et al. , 2010 (28)	Australia	Case-control	Not reported	Histologically confirmed	N = 32 Age $<$ 50 yr BMI = not reported	N = 522 Age $<$ 50 yr BMI = Not reported	Endometrial cancer	BMI	3.638 (1.761, 7.515)	High
Zuchetto et al. , 2009 (34)	Italy	Case-control	Not reported	Histologically confirmed	N = 68 Age = 18-79 BMI not reported	N = 1287 Age = 18-79 BMI not reported	Endometrial cancer	Period of interview, BMI, age at menarche, age at menopause, parity, and oral contraceptive use	1.171 (0.706, 1.943)	High
Olsen et al. , 2008 (30)	Australia	Case-control	Not reported	Histologically confirmed	N = 52 Age = 18-79 BMI not reported	N = 3047 Age = 18-79 BMI not reported	Ovarian cancer	Age, education, parity, hormonal contraceptive use, and BMI	1.15 (0.66, 1.99)	High
Wild et al. , 2000 (26)	UK	Cohort	Laparoscopic	ICD-7 and ICD-8	N = 319 Age = 38-98 BMI = 27.1	N = 1060 Age = 38-98 BMI = 26.2	Endometrial and breast cancer	BMI	Endometrial cancer OR: 5.923 (1.721, 20.365) breast cancer OR: 1.21 (0.63, 2.31)	High
Anderson et al. , 1997 (17)	USA	Cohort	Not reported	ICD codes 174.0-174.9	N = 472 Age = 55-69 BMI = 27.2 $\pm$ 0.23	N = 34363 Age = 55-69 BMI = 27 $\pm$ 0.03	Breast cancer	Age, age at menarche, age at first pregnancy, parity, oral contraceptive use, hormone replacement therapy, BMI, waist to hip ratio, benign breast disease, and family history of breast cancer	1.18 (0.69, 2.01)	Moderate
Talamini et al. , 1997 (32)	Italy	Case-control	Not reported	Histologically confirmed	N = 30 Age = 20-74 BMI not reported	N = 5127 Age = 20-74 BMI not reported	Breast cancer	Age at menarche	0.88 (0.43, 1.81)	Moderate
Schildkraut et al. , 1996 (13)	USA	Case-control	Not reported	Histologically confirmed	N = 31 Age = 20-54 BMI not reported	N = 4526 Age = 20-54 BMI not reported	Ovarian cancer	Age, parity, and oral contraceptive use	2.52 (1.08, 5.89)	High
Escobedo et al. , 1991 (31)	Georgia	Case-control	Not reported	Histologically confirmed	N = 30 Age = 20-54 BMI not reported	N = 3593 Age = 20-54 BMI not reported	Endometrial cancer	Age	3.757 (1.747, 8.081)	Moderate
PCOS: Polycystic ovary syndrome, BMI: Body mass index, N: Number, OR: Odds ratio, ICD: International classification of disease, NIH: National institute of health, ICD-9-CM: International classification of diseases, ninth revision, clinical modification, GPRD: General practice research database