Table 2.
Characteristics of young-onset breast cancer casesincluded in the genotyping analysis (n=1279).
| N (%) | ||
|---|---|---|
| Age at diagnosis | ||
| <40 | 136 (11) | |
| 40–49 | 1143 (89) | |
| Menopausal Status at Diagnosis | ||
| Premenopausal | 1186 (93) | |
| Postmenopausal | 86 (7) | |
| Missing | 7 | |
| Invasive Status | ||
| Ductal carcinoma in situ | 206 (16) | |
| Invasive | 1057 (84) | |
| Missing | 16 | |
| Estrogen Receptor Status | ||
| Positive | 1013 (81) | |
| Negative | 239 (19) | |
| Missing | 27 | |
| BRCA1/2 statusa | ||
| Case carries BRCA1/2 mutation | 100 (8) | |
| Case not known to have | 1179 (92) | |
| BRCA1/2 mutation | ||
a
Families were categorized as BRCA1 or BRCA2 mutation positive if (1) the case sister reported that she had had a positive test or (2) the case sister was not tested but the unaffected sister reported that she had had a positive test.