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Table 1 Distributions of serum human epidermal growth factor receptor-2 (HER2) extracellular domain (ECD) levels and proportions of patients with elevated serum HER2 ECD levels (i.e., >15.2 ng/ml) according to subgroups stratified according to various clinicopathologic variables ( n= 2,862)

From: Preoperative serum HER2 extracellular domain levels in primary invasive breast cancer

Subgroup classified by variables n(%) Serum HER2 ECD level (ng/ml) P a Patients with HER2 ECD >15.2 ng/ml
  Mean ± SD Median (range)   n %b
Total patients 2,862 (100%) 10.1 ± 9.4 9.2 (3.3–427.8)   126 4.4%
Age, years     0.149   
  ≤ 34 172 (6%) 10.1 ± 5.6 8.8 (4.8–56.0)   10 5.8%
 35–49 1,510 (53%) 9.8 ± 12.1 8.8 (3.3–427.8)   55 3.6%
  ≥ 50 1,180 (41%) 10.5 ± 9.4 9.8 (4.4–90.1)   61 5.2%
Stage     <0.001   
 I/II 2,457 (86%) 9.6 ± 4.6 9.1 (3.3–184.3)   81 3.3%
 III 405 (14%) 12.8 ± 22.1 10.1 (5.5–427.8)   45 11.1%
Tumor size, cm     0.001   
  ≤ 2 1,676 (59%) 9.6 ± 5.1 9.0 (3.3–184.3)   51 3.0%
  > 2 1,186 (41%) 10.8 ± 13.2 9.5 (3.8–427.8)   75 6.3%
Lymph node     <0.001   
 Negative 1,749 (61%) 9.6 ± 3.0 9.0 (3.3–48.2)   55 3.1%
 Positive 1,113 (39%) 11.0 ± 14.6 9.4 (4.3–427.8)   71 6.4%
Histologic grade       
 1/2 1,787 (64%) 9.7 ± 5.5 9.0 (3.8–184.3) 0.002 53 3.0%
 3 1,025 (36%) 10.8 ± 13.8 9.5 (4.6–427.8)   71 6.9%
 Unknown 50     2  
Nuclear grade     0.006   
 1/2 1,775 (63%) 9.6 ± 5.4 9.0 (3.3–184.3)   45 2.5%
 3 1,049 (37%) 10.6 ± 13.6 9.4 (4.6–427.8)   65 6.2%
 Unknown 38     16  
LVI     0.018   
 Negative 2,095 (76%) 9.8 ± 3.7 9.1 (3.3–67.5)   88 4.2%
 Positive 660 (24%) 10.3 ± 8.5 9.3 (3.8–184.3)   29 4.4%
 Unknown 107     9  
Hormone-receptor status     <0.001   
 Negative 916 (32%) 11.5 ± 15.0 9.8 (4.6–427.8)   85 9.3%
 Positivec 1,940 (68%) 9.5 ± 4.7 9.0 (3.3–184.3)   41 2.1%
 Unknown 6     0  
Tissue HER2 status     <0.001   
 Negative 2,168 (76%) 9.3 ± 4.3 8.9 (3.8–184.3)   22 1.0%
 Positived 692 (24%) 12.8 ± 17.3 10.6 (3.3–427.8)   104 15.0%
 Unknown 2     0  
Definitive surgery     <0.001   
 Conservation 1,781 (62%) 9.3 ± 2.5 8.9 (3.3–44.8)   38 2.1%
 Mastectomy 1,081 (38%) 11.4 ± 14.9 9.7 (4.3–427.8)   88 8.1%
Radiotherapy     0.135   
 Yes 2,047 (72%) 9.9 ± 10.2 9.1 (3.3–427.8)   74 3.6%
 No 813 (28%) 10.5 ± 7.1 9.6 (4.3–184.3)   52 6.4%
 Unknown 2     0  
Chemotherapy     <0.001   
 Yes 1,852 (65%) 10.6 ± 11.5 9.4 (4.3–427.8)   106 5.7%
 No 1,007 (35%) 9.2 ± 2.6 8.9 (3.3–35.6)   20 2.0%
 Unknown 3     0  
Anti-HER2 therapy     <0.001   
 Yes 264 (9%) 15.0 ± 27.2 11.0 (4.3–427.8)   53 20.1%
 No 2,598 (91%) 9.6 ± 4.4 9.1 (3.3–184.3)   73 2.8%
  1. aCalculated by ANOVA.
  2. bPercentage calculated by dividing the number of patients with elevated serum HER2 ECD level (>15.2 ng/ml) by the total number of patients in each subgroup.
  3. cEstrogen- and/or progesterone-receptor positive.
  4. dGraded as 3+ on immunohistochemistry (IHC) or 2+ on fluorescence in situ hybridization in cases of IHC 2+.
  5. LVI lymphovascular invasion.