Table 1.
Baseline Characteristics of Patients Diagnosed With Hormone Receptor–Positive Breast Cancer, Stages I-III, Who Received Adjuvant Endocrine Therapy, KPNC, 1996-2006
| Characteristic | All Patients (N = 8,769) |
Tamoxifen Only (n = 3,802) |
Aromatase Inhibitors Only (n = 2,313) |
|||
|---|---|---|---|---|---|---|
| No. | % | No. | % | No. | % | |
| Discontinued by 4.5 years | 2,790 | 32 | 1,460 | 38 | 659 | 29 |
| Nonadherent by 4.5 years | 1,666 | 28* | 702 | 30* | 465 | 28* |
| Age at diagnosis, years | ||||||
| < 50 | 1,472 | 16.8 | 910 | 23.9 | 89 | 3.9 |
| 50-64 | 3,609 | 41.2 | 1,312 | 34.5 | 1,082 | 46.8 |
| ≥ 65 | 3,688 | 42.1 | 1,580 | 41.6 | 1,142 | 49.4 |
| Year at diagnosis | ||||||
| > 2001 | 4,885 | 55.7 | 1,294 | 34.0 | 2,244 | 97.0 |
| ≤ 2001 | 3,884 | 44.3 | 2,508 | 66.0 | 69 | 3.0 |
| Race/ethnicity | ||||||
| White | 6,687 | 76.2 | 2,869 | 75.5 | 1,762 | 76.2 |
| Black | 488 | 5.6 | 225 | 5.9 | 121 | 5.2 |
| Hispanic | 630 | 7.2 | 260 | 6.8 | 169 | 7.3 |
| Asian | 964 | 11.0 | 448 | 11.8 | 261 | 11.3 |
| Marital status | ||||||
| Unmarried | 3,525 | 40.2 | 1,525 | 40.1 | 1,006 | 43.5 |
| Married | 5,244 | 59.8 | 2,277 | 59.9 | 1,307 | 56.5 |
| Socioeconomic status | ||||||
| Lowest quintile | 1,129 | 12.9 | 511 | 13.4 | 286 | 12.4 |
| 2nd quintile | 2,090 | 23.8 | 867 | 22.8 | 580 | 25.1 |
| 3rd quintile | 1,993 | 22.7 | 864 | 22.7 | 516 | 22.3 |
| 4th quintile | 1,662 | 19.0 | 764 | 20.1 | 448 | 19.4 |
| Highest quintile | 1,895 | 21.6 | 796 | 20.9 | 483 | 20.9 |
| Comorbidity score | ||||||
| 0 | 7,650 | 87.2 | 3,295 | 86.7 | 1,964 | 84.9 |
| 1 | 915 | 10.4 | 413 | 10.9 | 288 | 12.5 |
| ≥ 2 | 204 | 2.3 | 94 | 2.5 | 61 | 2.6 |
| Tumor size, cm | ||||||
| 0-< 1 | 2,377 | 27.1 | 1,102 | 29.0 | 686 | 29.7 |
| 1-2 | 3,929 | 44.8 | 1,711 | 45.0 | 982 | 42.5 |
| > 2 | 1,969 | 22.5 | 765 | 20.1 | 562 | 24.3 |
| Unknown | 494 | 5.6 | 224 | 5.9 | 83 | 3.6 |
| Tumor grade | ||||||
| Low (1 or 2) | 6,310 | 72.0 | 2,726 | 71.7 | 1,692 | 73.2 |
| High (3 or 4) | 1,475 | 16.8 | 610 | 16.0 | 392 | 17.0 |
| Unknown | 984 | 11.2 | 466 | 12.3 | 229 | 9.9 |
| Lymph node involvement | ||||||
| Negative | 7,961 | 90.8 | 3,577 | 94.1 | 2,002 | 86.6 |
| Positive | 808 | 9.2 | 225 | 5.9 | 311 | 13.5 |
| Surgery | ||||||
| Mastectomy | 3,190 | 36.4 | 1,454 | 38.2 | 715 | 30.9 |
| Lumpectomy | 5,407 | 61.7 | 2,292 | 60.3 | 1,537 | 66.5 |
| No/unknown | 172 | 2.0 | 56 | 1.5 | 61 | 2.6 |
| Chemotherapy | ||||||
| No/unknown | 6,415 | 73.2 | 2,932 | 77.1 | 1,761 | 76.1 |
| Yes | 2,354 | 26.8 | 870 | 22.9 | 552 | 23.9 |
| Radiation | ||||||
| No/unknown | 4,622 | 52.7 | 2,020 | 53.1 | 1,207 | 52.2 |
| Yes | 4,147 | 47.3 | 1,782 | 46.9 | 1,106 | 47.8 |
| Prescription refill interval, days | ||||||
| 30 | 1,764 | 20.1 | 957 | 25.2 | 321 | 13.9 |
| 60 | 1,323 | 15.1 | 902 | 23.7 | 69 | 3.0 |
| 90 | 5,682 | 64.8 | 1,943 | 51.1 | 1,923 | 83.1 |
| Types of endocrine therapy | ||||||
| Tamoxifen only | 3,802 | 43.4 | — | — | — | — |
| Aromatase inhibitors only | 2,313 | 26.4 | — | — | — | — |
| Anastrozole only | 1,964 | 84.9 | ||||
| Letrozole only | 133 | 5.8 | ||||
| Exemestane only | 19 | 0.8 | ||||
| Tamoxifen and aromatase inhibitors | 2,654 | 30.3 | — | — | — | — |
Abbreviation: KPNC, Kaiser Permanente of Northern California.
*
Denominator is the number of patients that continued on treatment.