Table 4 Subgroup analyses for evaluating histologic types of endometriosis-associated ovarian cancer

From: Risk and prognosis of ovarian cancer in women with endometriosis: a meta-analysis

    

Heterogeneity

 

Category

No. of studies with references

RR

95% CI

P

I 2

Model used

Serous carcinoma

Study design

 Case–control

15

0.774

0.654–0.915

<0.001

66.897

Random effects

 Cohort

2

0.371

0.218–0.642

0.349

0

Fixed effect

Quality of study (NOS)

 ⩾7

13

0.729

0.591–0.900

<0.001

74.977

Random effects

 <7

4

0.772

0.630–0.946

0.435

0

Fixed effect

Assessment of endometriosis

 Histology

3

0.408

0.064–2.585

<0.001

94.296

Random effects

 Self-report

13

0.776

0.709–0.851

0.854

0

Fixed effect

Adjustment for potential confounding factors

 Two factorsa

15

0.793

0.687–0.916

0.004

56.276

Random effects

 Eight factorsb

14

0.767

0.701–0.840

0.685

0

Fixed effect

Mucinous carcinoma

Study design

 Case–control

15

0.777

0.559–1.080

0.698

0

Fixed effect

 Cohort

2

1.475

0.377–5.768

0.227

31.613

Fixed effect

Quality of study (NOS)

 ⩾7

13

0.887

0.612–1.285

0.474

0

Fixed effect

 <7

4

0.606

0.321–1.144

0.934

0

Fixed effect

Assessment of endometriosis

 Histology

3

0.565

0.106–3.001

0.091

58.373

Random effects

 Self-report

13

0.753

0.530–1.069

0.900

0

Fixed effect

Adjustment for potential confounding factors

 Two factorsa

15

0.852

0.614–1.181

0.759

0

Fixed effect

 Eight factorsb

14

0.795

0.565–1.120

0.826

0

Fixed effect

Endometrioid carcinoma

Study design

 Case–control

15

1.684

1.479–1.917

0.611

0

Fixed effect

 Cohort

2

3.886

1.457–10.360

0.067

70.206

Random effects

Quality of study (NOS)

 ⩾7

13

1.788

1.557–2.054

0.046

43.661

Fixed effect

 <7

4

1.630

1.210–2.194

0.790

0

Fixed effect

Assessment of endometriosis

 Histology

3

2.837

1.417–5.677

0.043

68.249

Random effects

 Self-report

13

1.595

1.380–1.843

0.692

0

Fixed effect

Adjustment for potential confounding factors

 Two factorsa

15

1.634

1.422–1.878

0.695

0

Fixed effect

 Eight factorsb

14

1.629

1.414–1.875

0.629

0

Fixed effect

Clear cell carcinoma

Study design

 Case–control

15

2.454

2.077–2.899

0.591

0

Fixed effect

 Cohort

2

4.514

1.905–10.693

0.085

66.234

Random effects

Quality of study (NOS)

 ⩾7

13

2.518

2.111–3.003

0.147

29.680

Fixed effect

 <7

4

3.012

2.100–4.321

0.500

0

Fixed effect

Assessment of endometriosis

 Histology

3

3.118

1.301–7.472

0.024

73.229

Random effects

 Self-report

13

2.504

2.103–2.981

0.484

0

Fixed effect

Adjustment for potential confounding factors

 Two factorsa

15

2.486

2.108–2.931

0.579

0

Fixed effect

 Eight factorsb

14

2.526

2.132–2.992

0.552

0

Fixed effect

  1. Abbreviations: CI=confidence interval; FIGO=International Federation of Gynecology and Obstetrics; NOS=Newcastle–Ottawa Scale; RR=risk ratio.
  2. aAdjusted for age and race.
  3. bAge, body mass index, breastfeeding, family history of ovarian cancer, history of tubal ligation, parity, race, and use of oral contraceptive.
Back to article page