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Table 1 Characteristics of 173 study participants with breast cancer in the Multiethnic Cohort

From: Involution of breast tissue and mammographic density

Characteristica Original study Involution study No involution Partial involution Complete involution P valueb
(0%) (1–74%) (≥75%)
Sample size (%) 279 173 32 (18.5) 89 (51.4) 52 (30.1) N/A
Age at diagnosis
  < 50 years 24 (8.6) 15 (8.7) 7 (21.9) 7 (7.9) 1 (1.9) 0.01
 50 to <55 years 56 (20.1) 42 (24.3) 6 (18.8) 25 (28.1) 11 (21.2)
 55 to <60 years 55 (19.7) 40 (23.1) 12 (37.5) 18 (20.2) 10 (19.2)
 60 to <65 years 44 (14.3) 31 (17.9) 3 (9.4) 17 (19.1) 11 (21.2)
 65+ years 104 (37.3) 45 (26.0) 4 (12.5) 22 (24.7) 19 (36.5)
Menopausal status (%)
 Premenopausal 76 (27.2) 53 (30.6) 12 (37.5) 28 (31.5) 13 (25.0) 0.47
 Postmenopausal 203 (72.8) 120 (69.4) 20 (62.5) 61 (68.5) 39 (75.0)
Ethnicity (%)
 Caucasian 97 (34.8) 58 (33.5) 7 (21.9) 35 (39.3) 16 (30.8) 0.39
 Japanese American 121 (43.4) 80 (46.2) 16 (50.0) 39 (43.8) 25 (48.1)
 Native Hawaiian 36 (12.9) 19 (11.0) 6 (18.8) 6 (6.7) 7 (13.5)
 Other 25 (8.9) 16 (9.3) 3 (9.4) 9 (7.7) 4 (7.7)
Parity
 Nulliparous 47 (16.9) 25 (14.4) 6 (18.8) 8 (9.0) 11 (21.2) 0.16
 1–2 children 110 (39.4) 69 (39.9) 15(46.9) 38 (42.7) 16 (30.8)
 3 or more children 122 (43.7) 79 (45.7) 11 (34.4) 43 (48.3) 25 (46.1)
Hormone use (%)
 Never 102 (36.5) 59 (34.1) 9 (28.1) 28 (31.5) 22 (42.3) 0.58
 Estrogen 97 (34.8) 62 (35.8) 11 (34.4) 34 (38.2) 17 (32.7)
 Estrogen/progesterone 80 (28.7) 52 (30.1) 12 (37.5) 27 (30.3) 13 (25.0)
Body mass index
  < 25 kg/m2 167 (59.9) 104 (60.1) 18 (56.3) 56 (62.9) 30 (57.7) 0.60
 25 to <30 kg/m2 81 (29.0) 54 (31.2) 12 (37.5) 27 (30.3) 17 (28.9)
 30+ kg/m2 31 (11.1) 15 (8.7) 2 (6.3) 6 (6.7) 7 (13.5)
Tumor stage (%)
In situ 61 (21.9) 39 (22.6) 10 (31.3) 18 (20.2) 11 (21.2) 0.60
 Localized 169 (60.6) 105 (60.7) 20 (62.5) 53 (59.6) 32 (61.5)
 Advanced 37 (13.2) 21 (12.1) 2 (6.3) 13 (14.6) 6 (11.5)
 Missing 12 (4.3) 8 (4.6) 0 (0.0) 5 (5.6) 3 (5.8)
Mammographic measures
 Percent density 37.6 41.2 38.8 42.8 40.0 0.96
 Dense area (cm2) 37.8 40.8 32.6 41.6 44.7 0.04
 Non-dense area (cm2) 77.5 67.8 63.9 64.9 75.1 0.24
 Total area (cm2) 115.3 108.6 96.5 106.4 119.5 0.02
  1. aNumbers and percentages except for mammographic measures; percentages may not add up to 100 due to rounding
  2. bBased on the chi-square test for categorical variables and general linear models for continuous variables