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Table 1 Selected characteristics of the study population

From: A population-based study of tumor gene expression and risk of breast cancer death among lymph node-negative patients

Characteristic Cases (n = 220) Controls (n = 570)
Matched variables     
Age at diagnosis (years)     
   <40 17 (8%) 23 (4%)
   40–49 42 (19%) 127 (22%)
   50–59 64 (29%) 152 (27%)
   60–74 97 (44%) 268 (47%)
Race/ethnicity     
   White, non-Hispanic 172 (78%) 457 (80%)
   White, Hispanic 7 (3%) 13 (2%)
   Black 20 (9%) 47 (8%)
   Asian 21 (10%) 53 (9%)
Surgery year     
   1985–1989 146 (66%) 385 (68%)
   1990–1994 74 (34%) 185 (32%)
Adjuvant tamoxifen     
   No 156 (71%) 393 (69%)
   Yes 64 (29%) 177 (31%)
Unmatched variables     
ER status from RT-PCR1     
   Positive 168 (76%) 514 (90%)
   Negative 52 (24%) 56 (10%)
Tumor size (cm)     
   ≤1 49 (22%) 193 (34%)
   1.1–2 93 (42%) 255 (45%)
   2.1–4 72 (33%) 114 (20%)
   >4 6 (3%) 8 (1%)
Tumor grade (differentiation)2     
   Well 25 (11%) 175 (31%)
   Moderate 92 (42%) 261 (46%)
   Poor 103 (47%) 134 (23%)
Recurrence Score     
   Low risk (<18) 57 (26%) 322 (56%)
   Intermediate risk (18–30) 54 (25%) 108 (19%)
   High risk (≥31) 109 (50%) 140 (25%)
  1. 1Cutoff points based on RT-PCR values: ≤6.5 and >6.5 units. 2Bloom-Richardson grading criteria, pathologist 1. ER, estrogen receptor; RT-PCR, reverse transcription polymerase chain reaction.