Table 1.
Clinical characteristics and their relationship with extending therapy after finishing 5-years adjuvant hormone therapy in women diagnosed with breast cancer in Stockholm, Sweden, 2005–2020.
| OR (95% CI) | ||||
|---|---|---|---|---|
| Characteristics | Total | Extended therapya, (%) | Age-adjusted | Multivariableb |
| Age at diagnosis (years) | ||||
| <40 | 155 | 87 (56.1) | 3.81 (2.71–5.36) | 1.71 (1.13–2.58) |
| 40–49 | 848 | 384 (45.3) | 2.46 (2.05–2.96) | 1.72 (1.36–2.17) |
| 50–64 | 2,002 | 590 (29.5) | 1.24 (1.06–1.46) | 1.01 (0.83–1.23) |
| ≥65 | 1,293 | 325 (25.1) | 1.00 (reference) | 1.00 (reference) |
| Therapy type at baseline | ||||
| Tamoxifen | 2,636 | 683 (25.9) | 1.00 (reference) | 1.00 (reference) |
| Aromatase inhibitors | 1,662 | 703 (42.3) | 3.54 (3.03–4.13) | 1.13 (0.93–1.38) |
| Tumor size (mm) | ||||
| ≤20 | 2,768 | 716 (25.9) | 1.00 (reference) | 1.00 (reference) |
| >20 | 1,517 | 665 (43.8) | 2.13 (1.86–2.44) | 1.03 (0.87–1.23) |
| Lymph node involvement | ||||
| Negative | 2,896 | 628 (21.7) | 1.00 (reference) | 1.00 (reference) |
| Positive | 1,335 | 730 (54.7) | 4.21 (3.66–4.86) | 2.25 (1.85–2.73) |
| Elston–Ellis tumor grade | ||||
| 1 | 920 | 139 (15.1) | 1.00 (reference) | 1.00 (reference) |
| 2 | 2,191 | 603 (27.5) | 2.13 (1.73–2.61) | 1.37 (1.08–1.74) |
| 3 | 842 | 428 (50.8) | 5.36 (4.27–6.74) | 1.79 (1.34–2.39) |
| Progesterone receptor status | ||||
| Positive | 3,523 | 1,112 (31.6) | 1.00 (reference) | 1.00 (reference) |
| Negative | 696 | 234 (33.6) | 1.22 (1.02–1.46) | 1.01 (0.81–1.25) |
| HER2 statusc | ||||
| Negative | 3,216 | 1,078 (33.5) | 1.00 (reference) | 1.00 (reference) |
| Positive | 335 | 196 (58.5) | 2.46 (1.94–3.11) | 1.03 (0.78–1.36) |
| Chemotherapy | ||||
| No | 2,457 | 311 (12.7) | 1.00 (reference) | 1.00 (reference) |
| Yes | 1,789 | 1,057 (59.1) | 9.68 (8.27–11.34) | 5.22 (4.19–6.50) |
| Radiotherapy | ||||
| No | 577 | 159 (27.6) | 1.00 (reference) | 1.00 (reference) |
| Yes | 3,673 | 1,206 (32.8) | 1.36 (1.12–1.67) | 0.85 (0.67–1.08) |
| Breast cancer among female first-degree relatives | ||||
| No | 3,371 | 1,068 (31.7) | 1.00 (reference) | 1.00 (reference) |
| Yes | 619 | 210 (33.9) | 1.16 (0.96–1.39) | 1.16 (0.93–1.45) |
| Death from breast cancer among female first-degree relatives | ||||
| No | 3,844 | 1,218 (31.7) | 1.00 (reference) | 1.00 (reference) |
| Yes | 146 | 60 (41.1) | 1.66 (1.18–2.34) | 1.84 (1.21–2.81) |
| Education (years) | ||||
| ≤9 | 623 | 172 (27.6) | 1.00 (reference) | 1.00 (reference) |
| 9–12 | 1,688 | 527 (31.2) | 1.07 (0.87–1.32) | 1.10 (0.85–1.41) |
| >12 | 1,958 | 674 (34.4) | 1.20 (0.98–1.47) | 1.24 (0.97–1.58) |
| Income | ||||
| Low | 1,432 | 419 (29.3) | 1.00 (reference) | 1.00 (reference) |
| Middle | 1,433 | 427 (29.8) | 0.94 (0.80–1.11) | 0.85 (0.69–1.03) |
| High | 1,433 | 540 (37.7) | 1.37 (1.16–1.61) | 1.23 (1.01–1.49) |
aExtended adjuvant hormone therapy was a binary outcome, which was defined as continuing the therapy for ≥6 months and filling ≥2 prescriptions of tamoxifen or aromatase inhibitors beyond the 5-year adjuvant hormone therapy.
bAdjusted for age at diagnosis, calendar period of cancer diagnosis, tumor size, lymph node status, tumor grade, progesterone receptor status, chemotherapy, and radiotherapy.
cHER2 status was recorded from 2007.