TABLE 1.
Study population characteristics.
| Characteristics | Cases (N = 990) | Controls (N = 1,094) |
|---|---|---|
| Age a | ||
| Mean ± sd—years | 51.5 ± 9.3 | 55.7 ± 6.9 |
| Range—years | 26–74 | 28–71 |
| Age Distribution—N/total N. (%) | ||
| ≤29 | 5/990 (0.5%) | 2/1,091 (0.2%) |
| 30–39 | 87/990 (8.8%) | 8/1,091 (0.7%) |
| 40–49 | 349/990 (35.3%) | 178/1,091 (16.3%) |
| 50–59 | 344/990 (34.7%) | 566/1,091 (51.9%) |
| ≥60 | 205/990 (20.7%) | 337/1,091 (30.9%) |
| Family history of breast cancer b —N/total N. (%) | ||
| No | 815/973 (83.8%) | 1,004/1,091 (92.0%) |
| Yes | 158/973 (16.2%) | 87/1,091 (8.0%) |
| Histological subtype—N/total N. (%) | ||
| Invasive | 656/709 (92.5%) | NA |
| In situ | 53/709 (7.5%) | NA |
| ER status—N/total N. (%) | ||
| ER-negative | 152/628 (24.2%) | NA |
| ER-positive | 476/628 (75.8%) | NA |
| PR status—N/total N. (%) | ||
| PR-negative | 238/619 (38.4%) | NA |
| PR-positive | 381/619 (61.6%) | NA |
| HER2 status—N/total N. (%) | ||
| HER2-negative | 490/584 (83.9%) | NA |
| HER2-positive | 94/584 (16.1%) | NA |
| Breast cancer subtypes c – N/total N. (%) | ||
| Triple-negative | 66/576 (11.5%) | NA |
| ER-positive | 441/576 (76.6%) | NA |
| PR-positive | 362/576 (62.8%) | NA |
| HER2-positive | 93/576 (16.1%) | NA |
a
Age is denoted as the age at diagnosis for cases or age at interview for controls.
b
family history was restricted to first-degree relatives.
c
breast cancer subtypes for tumors that have data available for all ER, PR, and HER2 biomarkers.
Estrogen receptor; HER2, human epidermal growth factor receptor 2; NA, non-applicable; PR, progesterone receptor; sd, standard deviation.