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Table 1 Characteristics of the nested case-control studies included in the meta-analysis

From: Blood DNA methylation and breast cancer risk: a meta-analysis of four prospective cohort studies

Characteristics

Melbourne Collaborative Cohort Study

European Prospective Investigation into Cancer and Nutrition (Italy)

European Prospective Investigation into Cancer and Nutrition (IARC)

Prostate, Lung, Colorectal and Ovarian Screening Trial

Acronym

MCCS

EPIC-Italy

EPIC-IARC

PLCO

Reference

(17)

(18)

(19)

–

Location

Australia

Italy

Germany, Greece, Italy, Spain, The Netherlands, and the UK

US

Methylation array used

HM450K

HM450K

HM450K

EPIC

Number of subjects, n

 Controls (N = 1926)

409

248

423

805

 Cases (N = 1703)

409

248

423

583

Age at blood draw (years), mean (SD)

56.7 (7.9)

52.2 (7.2)

52.2 (9.0)

62.2 (5.2)

Time from blood draw to diagnosis in cases

 Median (IQR)

7.7 (4.4., 11.1)

6.55 (2.5, 10.6)

7.7 (5.0, 10.3)

8.4 (5.6, 10.5)

 Average (SD)

7.6 (3.9)

6.7 (4.4)

7.5 (3.2)

7.9 (3.5)

ER status, n (%)

 Positive

297 (72.6)

147 (59.3)

350 (82.7)

411 (70.5)

 Negative

103 (25.2)

30 (12.0)

73 (17.3)

78 (12.9)

Stage†, n (%)

 Early

246 (60.1)

71 (28.6)

207 (48.9)

337 (57.8)

 Late

141 (34.5)

40 (16.1)

95 (22.5)

183 (31.4)

  1. SD standard deviation, IQR interquartile range, ER estrogen receptor
  2. †Stage: a cancer was considered an early stage if it was classified as localized (EPIC-Italy, EPIC-IARC) or stage I (MCCS, PLCO). A cancer was considered late-stage if it was classified as regional or metastatic (EPIC-Italy, EPIC-IARC) or stages II, III, or IV (MCCS, PLCO)