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Table 2 Association between tumor characteristics of first primary breast cancer and contralateral breast cancer risk

From: Hormone receptor status of a first primary breast cancer predicts contralateral breast cancer risk in the WECARE study population

First primary breast cancer

Cases, N (%)

Controls, N (%)

RRa (95% CI)

Histology

 Non-lobular

1338 (88)

1986 (90)

1.0 (ref.)

 Lobular

179 (12)

223 (10)

1.3 (1.0, 1.6)

 Unknown

4 (0)

3 (0)

 

Grade

 Well

248 (16)

338 (15)

1.0 (ref.)

 Moderate

417 (27)

688 (31)

0.8 (0.7, 1.1)

 Poor/undifferentiated

503 (33)

640 (29)

1.1 (0.8, 1.4)

 Unknown

353 (23)

546 (25)

 

Stage

 Localized

1061 (70)

1442 (65)

1.0 (ref.)

 Regional

448 (29)

759 (34)

1.0 (0.9, 1.2)

 Unknown

12 (1)

11 (1)

 

Lymph node status

 Negative

1045 (69)

1426 (64)

1.0 (ref.)

 Positive

438 (29)

751 (34)

1.0 (0.8, 1.2)

 No nodes sampled

22 (2)

26 (1)

1.3 (0.7, 2.4)

 Unknown

16 (1)

9 (0)

 

Tumor size

 ≤10 mm

335 (22)

510 (23)

1.0 (ref.)

 >10 to ≤20 mm

595 (39)

913 (41)

1.1 (0.9, 1.3)

 >20 mm

477 (31)

662 (30)

1.1 (0.9, 1.4)

 Inflammatory

6 (0)

2 (0)

 

 Unknown

108 (7)

125 (6)

 

ER status

 Positive

797 (52)

1254 (57)

1.0 (ref.)

 Negative

467 (31)

561 (25)

1.3 (1.1, 1.6)

 Other/unknownb

257 (17)

397 (18)

 

PR status

 Positive

687 (45)

1083 (49)

1.0 (ref.)

 Negative

442 (29)

549 (25)

1.2 (1.0, 1.5)

 Other/unknownb

392 (26)

580 (26)

 

Joint ER/PR status

 ER+/PR+

621 (41)

958 (43)

1.0 (ref.)

 ER+/PR-

85 (6)

142 (6)

1.0 (0.7, 1.4)

 ER-/PR-

352 (23)

387 (18)

1.4 (1.1, 1.7)

 Other/unknownb,c

463 (30)

725 (33)

 

HER2 statusd

 Negative

207 (25)

222 (27)

1.0 (ref.)

 Positive

53 (7)

63 (8)

0.8 (0.5, 1.3)

 Unknownb

553 (68)

528 (65)

 

Triple-negatived

 No

514 (63)

579 (71)

1.0 (ref.)

 Yes

59 (7)

40 (5)

1.3 (0.8, 2.2)

 Other/unknownb

240 (30)

194 (24)

 
  1. Abbreviations: RR risk ratio, CI confidence interval, N number, ER estrogen receptor, PR progesterone receptor, HER2 human epidermal growth factor receptor 2. aAdjusted for age at first breast cancer diagnosis, first-degree family history of breast cancer, histologic assessment, menopausal status, age at menarche, parity, radiation, chemotherapy and hormone therapy at first breast cancer diagnosis. Model examining histology was not adjusted for histologic assessment. b“Other/unknown” category consists of women for whom no laboratory test was given, the test was given and the results were unknown or the test was given and the results were borderline; estimates not reported. The start date for ER/PR reporting in SEER was 1 January 1990 [47]. cIncludes 59 cases and 108 controls classified as ER-/PR+. dAmong participants in the Women’s Environmental Cancer and Radiation Epidemiology II Study (WECARE II) only; HER2 status not queried for WECARE I participants. Surveillance, Epidemiology, and End Results (SEER) Registry only began collecting HER2 status in 2010 [46]