Table 1.

Distribution of demographic and risk factors by breast cancer subtype

Luminal A (N = 785)Luminal B (N = 133)Triple-negative (N = 1299)HER2-overexpressing (N = 493)
Variablesn, %n, %n, %n, %
Year at diagnosis
 2004–2006277 (35.3)47 (35.3)436 (33.6)158 (32.0)
 2007–2008209 (26.6)28 (21.1)347 (26.7)127 (25.8)
 2009–2010159 (20.3)32 (24.1)295 (22.7)113 (22.9)
 2011–2012140 (17.8)26 (19.5)221 (17.0)95 (19.3)
Study site
 Seattle596 (75.9)92 (69.2)992 (76.4)349 (70.8)
 New Mexico189 (24.1)41 (30.8)307 (23.6)144 (29.2)
Age at diagnosis (in years)
 <4098 (12.5)27 (20.3)189 (14.5)53 (10.8)
 40–49210 (26.8)46 (34.6)361 (27.8)119 (24.1)
 50–59272 (34.6)41 (30.8)416 (32.0)194 (39.4)
 60–69205 (26.1)19 (14.3)333 (25.6)127 (25.8)
Race/ethnicity
 Non-Hispanic white613 (79.2)94 (72.3)987 (76.5)374 (76.6)
 Hispanic white77 (9.9)23 (17.7)126 (9.8)57 (11.7)
 African American25 (3.2)4 (3.1)102 (7.9)22 (4.5)
 Asian/Pacific Islander48 (6.2)5 (3.8)46 (3.6)24 (4.9)
 Native American11 (1.4)4 (3.1)30 (2.3)11 (2.3)
 Missing11385
Health insurance status
 Any private646 (84.2)101 (78.3)1,043 (82.4)393 (82.2)
 Any Medicaid54 (7.0)11 (8.5)83 (6.6)28 (5.9)
 Medicare42 (5.5)11 (8.5)99 (7.8)35 (7.3)
 No insurance25 (3.3)6 (4.7)41 (3.2)22 (4.6)
 Missing1843315
First-degree family history of breast cancer
 No577 (76.7)103 (80.5)985 (77.7)381 (80.2)
 Yes175 (23.3)25 (19.5)282 (22.3)94 (19.8)
 Missing3353218
Menopausal status
 Premenopausal302 (39.6)69 (54.3)473 (37.5)154 (32.4)
 Perimenopausal66 (8.7)8 (6.3)105 (8.3)47 (9.9)
 Postmenopausal395 (51.8)50 (39.4)683 (54.2)275 (57.8)
 Missing2263817
Smoking status at breast cancer diagnosis
 Never454 (59.0)68 (53.1)739 (57.7)286 (59.0)
 Current107 (13.9)17 (13.3)196 (15.3)73 (15.1)
 Former209 (27.1)43 (33.6)345 (27.0)126 (26.0)
 Missing155198
Body mass index at diagnosis (kg/m2)
 <25.0283 (36.7)54 (41.9)435 (34.1)190 (39.3)
 25.0–29.9221 (28.6)40 (31.0)379 (29.7)147 (30.4)
 ≥30.0268 (34.7)35 (27.1)461 (36.2)146 (30.2)
 Missing1342410
Recency of menopausal hormone use at diagnosisa
 Never user619 (83.8)113 (90.4)1,005 (83.6)382 (84.3)
 Former user42 (5.7)7 (5.6)90 (7.5)38 (8.4)
 Current estrogen alone user34 (4.6)5 (4.0)81 (6.7)24 (5.3)
 Current estrogen + progestin user44 (6.0)0 (0.0)26 (2.2)9 (2.0)
 Missing4689740
Recency of hormonal oral contraceptive use at diagnosisa
 Never user620 (82.8)105 (85.4)1005 (81.8)409 (88.1)
 Former user38 (5.1)8 (6.5)87 (7.1)20 (4.3)
 Current user61 (8.1)6 (4.9)76 (6.2)24 (5.2)
 Ever user with unknown end date30 (4.0)4 (3.3)60 (4.9)11 (2.4)
 Missing36107129
  • aBased on use information within 5 years prior to diagnosis date.