Table 1.
Demographic and clinical characteristics by PAM50 tumor subtype*
| Characteristic | Luminal A, % | Luminal B, % | Basal-like, % | HER2-E, % | Total, % | P† |
|---|---|---|---|---|---|---|
| (n = 591) | (n = 365) | (n = 321) | (n = 359) | (n = 1636) | ||
| Age at breast cancer diagnosis, y | <.001 | |||||
| <50 | 17.8 | 29.9 | 36.8 | 21.7 | 23.0 | |
| 50–64 | 46.3 | 44.3 | 44.3 | 49.2 | 46.0 | |
| ≥65 | 35.9 | 25.8 | 19.0 | 29.1 | 31.0 | |
| mean | 60.5 | 57.4 | 54.5 | 58.9 | 58.9 | |
| Race/ethnicity | <.001 | |||||
| White | 75.1 | 74.0 | 62.0 | 70.2 | 72.7 | |
| African American | 4.8 | 3.6 | 19.7 | 6.4 | 6.4 | |
| Hispanic | 7.5 | 9.8 | 10.9 | 9.9 | 8.7 | |
| Asian | 10.6 | 10.3 | 4.7 | 9.2 | 9.7 | |
| Other | 1.9 | 2.3 | 2.6 | 4.4 | 2.5 | |
| Education | .44 | |||||
| High school or less | 20.5 | 18.8 | 20.6 | 24.6 | 20.8 | |
| Some college | 40.6 | 35.9 | 45.7 | 35.1 | 39.4 | |
| College graduate | 20.7 | 24.0 | 15.6 | 19.8 | 20.7 | |
| Postgraduate | 18.2 | 21.3 | 18.1 | 20.5 | 19.1 | |
| Smoking history at breast cancer diagnosis | .06 | |||||
| Never | 53.7 | 57.0 | 52.3 | 46.5 | 53.2 | |
| Past | 41.0 | 39.1 | 40.6 | 42.5 | 40.8 | |
| Current | 5.3 | 3.9 | 7.1 | 10.9 | 6.0 | |
| Menopausal status at breast cancer diagnosis | <.001 | |||||
| Postmenopausal | 73.4 | 63.9 | 54.4 | 69.9 | 68.7 | |
| Premenopausal | 19.7 | 32.0 | 36.8 | 23.2 | 24.7 | |
| Unknown | 6.9 | 4.1 | 8.8 | 6.8 | 6.5 | |
| AJCC stage | <.001 | |||||
| I | 57.0 | 36.8 | 43.0 | 38.7 | 48.5 | |
| II | 38.0 | 49.7 | 50.5 | 53.1 | 44.0 | |
| III | 4.9 | 12.6 | 5.3 | 7.1 | 6.9 | |
| IV | 0.1 | 0.9 | 1.2 | 1.1 | 0.6 | |
| Breast cancer surgery | .12 | |||||
| None | 0.5 | 1.5 | 0.6 | 0.7 | 0.7 | |
| Lumpectomy | 59.0 | 52.9 | 61.4 | 49.3 | 56.6 | |
| Mastectomy | 40.5 | 45.6 | 38.0 | 50.0 | 42.7 | |
| Chemotherapy | <.001 | |||||
| No | 64.9 | 38.4 | 19.7 | 28.7 | 48.90 | |
| Yes | 35.1 | 61.6 | 80.3 | 71.3 | 51.1 | |
| Radiotherapy | .05 | |||||
| No | 51.0 | 58.7 | 48.0 | 59.3 | 53.6 | |
| Yes | 49.0 | 41.3 | 52.0 | 40.7 | 46.4 | |
| Hormonal therapy | <.001 | |||||
| No | 17.6 | 11.8 | 95.2 | 45.4 | 29.0 | |
| Yes | 82.4 | 4.8 | 4.8 | 54.6 | 71.0 | |
| Any comorbidity (Charlson comorbidity index) | .82 | |||||
| No | 86.2 | 87.1 | 84.8 | 88.2 | 86.5 | |
| Yes | 13.8 | 12.9 | 15.2 | 11.8 | 13.5 | |
| Tumor subtype by immunohistochemistry | <.001 | |||||
| ER+PR+HER2- | 93.4 | 76.3 | 9.7 | 34.6 | 71.9 | |
| ER+PR+HER2+ | 5.7 | 19.4 | 1.2 | 24.1 | 10.8 | |
| ER-PR-HER2- | 0.7 | 2.9 | 83.3 | 18.3 | 12.8 | |
| ER-PR-HER2+ | 0.2 | 1.5 | 5.9 | 23.0 | 4.4 | |
| Parity‡ and breastfeeding | .002 | |||||
| Nulliparous | 15.6 | 25.8 | 17.0 | 13.9 | 17.7 | |
| Parous, no | 26.7 | 18.4 | 35.4 | 28.4 | 26.1 | |
| Parous, <6 mo BF | 22.5 | 19.4 | 17.4 | 25.6 | 21.7 | |
| Parous, ≥6 mo BF | 35.2 | 36.4 | 30.2 | 32.1 | 34.5 | |
* Percentages are weighted because of stratified case-cohort study design with strata defined as immunohistochemistry clinical subtype. AJCC = American Joint Committee on Cancer; BF = breastfeeding; ER = estrogen receptor; HER2 = human epidermal growth factor receptor 2; PR = progesterone receptor.
† From two-sided Pearson-chi-square test.
‡ Parous is at least one live or stillbirth (range 1–10); nulliparous is no live or stillbirth.