Table 1.

Characteristics of patients with CBC and control patients

ControlsPatients with CBC
n = 661n = 352
n (%)n (%)
Demographic characteristics
 Age at first breast cancer diagnosis, y
  40–49120 (18.2)69 (19.6)
  50–59174 (26.3)89 (25.3)
  60–69206 (31.2)108 (30.7)
  70–79161 (24.4)86 (24.4)
 Reference age, y
  40–4959 (8.9)33 (9.4)
  50–59129 (19.5)66 (18.8)
  60–69211 (31.9)111 (31.5)
  70–79199 (30.1)103 (29.3)
  80–8963 (9.5)39 (11.1)
 Year of first breast cancer diagnosis
  1990–1993241 (36.5)131 (37.2)
  1994–1997220 (33.3)115 (32.7)
  1998–2001147 (22.2)79 (22.4)
  2002–200553 (8.0)27 (7.7)
 Race/ethnicity
  Non-Hispanic white606 (92.0)322 (92.0)
  Asian/Pacific Islander16 (2.4)9 (2.6)
  African American24 (3.6)11 (3.1)
  Native American10 (1.5)5 (1.4)
  Hispanic white3 (0.5)3 (0.9)
  Missing22
 Education
  High school or less173 (33.7)78 (31.5)
  High school or some college169 (32.9)102 (41.1)
  College graduates or higher172 (33.5)68 (27.4)
  Missing147104
Treatments for first breast cancer
 Received radiation therapy
  No229 (34.6)127 (36.1)
  Yes432 (65.4)225 (63.9)
 Received chemotherapy
  No488 (73.8)264 (75.0)
  Yes173 (26.2)88 (25.0)
 Received hormonal therapy, y
  None183 (27.7)130 (36.9)
  <1100 (15.1)56 (15.9)
  1–4195 (29.5)87 (24.7)
  ≥5183 (27.7)79 (22.4)
Tumor characteristics of first breast cancer
 AJCC stage
  I454 (68.7)231 (65.6)
  II/III207 (31.3)121 (34.4)
 Tumor size, cm
  ≤1.0229 (35.6)111 (33.0)
  1.1–2.0282 (43.8)136 (40.5)
  >2.0133 (20.7)89 (26.5)
  Missing1716
Established breast cancer risk factors
 First-degree family history of breast cancer
  No463 (74.3)227 (70.5)
  Yes160 (25.7)95 (29.5)
  Missing3830
 Number of full-term pregnancies
  Nulliparous98 (15.2)54 (15.9)
  1–2273 (42.5)149 (44.0)
  ≥3272 (42.3)136 (40.1)
  Missing1813
 Recency of menopausal hormone use at first breast cancer diagnosis
  Never292 (46.9)166 (50.9)
  Former71 (11.4)38 (11.7)
  Current estrogen alone user138 (22.2)70 (21.5)
  Current estrogen + progestin user122 (19.6)52 (16.0)
  Missing3826
Health status and lifestyle factors
 Had a diagnosis of hypertension between first breast cancer and reference date
  No330 (50.6)180 (51.9)
  Yes322 (49.4)167 (48.1)
  Missing95
 Had a diagnosis of heart disease between first breast cancer and reference date
  No495 (76.5)272 (78.8)
  Yes152 (23.5)73 (21.2)
  Missing147
 BMI at first breast cancer diagnosis, kg/m2
  <25284 (43.8)125 (36.5)
  25–29.9194 (29.9)112 (32.7)
  ≥30170 (26.2)105 (30.7)
  Missing1310
 Alcohol consumption between first breast cancer and reference date, drinks/wk
  None241 (47.2)113 (45.2)
  <3132 (25.8)71 (28.4)
  ≥3138 (27.0)66 (26.4)
  Missing150102
 Smoking status at reference date
  Never269 (52.2)120 (47.6)
  Former49 (9.5)35 (13.9)
  Current197 (38.3)97 (38.5)
  Missing146100

NOTE: Cases and controls were individually matched on age, year of diagnosis, county, race/ethnicity, and cancer stage. Controls also had to be alive for at least the duration between their matched cases' first and CBC diagnoses.