Table 2.

Breast cancer characteristics among women younger than 55 years across the Premenopausal Breast Cancer Collaborative Group

CharacteristicCombined (N)Total N studies with data availablea
Total breast cancers diagnosed21,76620 (all)
Age at diagnosis (y)20 (all)
<3032
30–391,245
40–443,340
45–497,053
50–5410,096
Extent of disease20
In situ3,651
Invasive17,357
Missing758
Estrogen receptor status16
Positive9,583
Negative3,182
Borderline52
Missing8,949
Progesterone receptor status16
Positive7,919
Negative3,939
Borderline95
Missing9,813
HER2/neu overexpression11
Positive1,093
Negative4,808
Borderline29
Missing15,836
  • aContributed as of June 2016.