Table 4.
Factors associated with conventional schedule vs. dose dense: how associations varied over time
| Characteristic | Early Years (2005-2011) | Late Years (2012-2019) | p-interaction | ||
|---|---|---|---|---|---|
|
| |||||
| N (%) | PRatio (95% CI)a | N (%) | PRatio (95% CI)a | ||
| TOTAL | 2493 (53) | - | 2192 (47) | - | - |
| Dose dense | 1,108 (44) | - | 1,681 (77) | - | - |
| Conventional schedule | 1,385 (56) | - | 511 (23) | - | - |
| Sociodemographics | |||||
| Age at diagnosis (years) | |||||
| 18-39 | 198 (7.9) | REF | 284 (13.0) | REF | <0.001 |
| 40-49 | 707 (28.4) | 1.16 (0.99, 1.38) | 609 (27.8) | 1.40 (1.02, 1.92) | |
| 50-64 | 1,228 (49.3) | 1.35 (1.15, 1.58) | 1,016 (46.4) | 1.61 (1.20, 2.18) | |
| 65-74 | 332 (13.3) | 1.81 (1.53, 2.14) | 258 (11.8) | 2.39 (1.72, 3.33) | |
| 75+ | 28 (1.1) | 2.13 (1.63, 2.76) | 25 (1.1) | 5.09 (3.46, 7.49) | |
| p-trend<0.001 | p-trend<0.001 | ||||
| Race and ethnicity | |||||
| Non-Hispanic White | 1,458 (58.5) | REF | 1,133 (51.7) | REF | 0.15 |
| Non-Hispanic Black/AA | 206 (8.3) | 1.05 (0.93, 1.18) | 184 (8.4) | 1.28 (1.01, 1.62) | |
| Non-Hispanic Asian | 421 (16.9) | 0.99 (0.90, 1.09) | 420 (19.2) | 1.03 (0.84, 1.26) | |
| Hispanic | 382 (15.3) | 1.04 (0.94, 1.14) | 416 (19.0) | 1.01 (0.82, 1.23) | |
| Other | 26 (1.0) | 1.07 (0.75, 1.53) | 39 (1.8) | 0.58 (0.25, 1.39) | |
| global p=0.86 | global p=0.17 | ||||
| Neighborhood level SES | |||||
| Median Household Income b | |||||
| Q1: <$66,392 | 657 (26.4) | REF | 580 (26.5) | REF | 0.003 |
| Q2: $66,392-<$89,107 | 614 (24.6) | 1.01 (0.93, 1.10) | 541 (24.7) | 0.68 (0.56, 0.83) | |
| Q3: $89,107-<$117,278 | 632 (25.4) | 0.92 (0.84, 1.00) | 567 (25.9) | 0.72 (0.59, 0.87) | |
| Q4: ≥$117,278 | 590 (23.7) | 0.80 (0.73, 0.89) | 504 (23.0) | 0.58 (0.47, 0.72) | |
| p-trend<0.001 | p-trend<0.001 | ||||
| Patient characteristics | |||||
| BMI at diagnosis (kg/m2) | |||||
| <18.5 | 32 (1.3) | 0.98 (0.69, 1.39) | 17 (0.8) | 1.53 (0.86, 2.71) | 0.06 |
| 18.5-<25 | 769 (30.8) | REF | 641 (29.2) | REF | |
| 25-<30 | 806 (32.3) | 0.99 (0.91, 1.08) | 689 (31.4) | 0.79 (0.66, 0.96) | |
| 30-<35 | 488 (19.6) | 1.03 (0.93, 1.13) | 453 (20.7) | 0.89 (0.73, 1.09) | |
| ≥35 | 398 (16.0) | 1.11 (1.01, 1.22) | 392 (17.9) | 0.80 (0.64, 1.01) | |
| p-trend=0.04 | p-trend=0.07 | ||||
| Diabetes | |||||
| No | 2,286 (91.7) | REF | 1,964 (89.6) | REF | 0.85 |
| Yes | 207 (8.3) | 1.11 (1.00, 1.23) | 228 (10.4) | 1.04 (0.83, 1.29) | |
| CVD | |||||
| No | 2,404 (96.4) | REF | 2,157 (98.4) | REF | 0.75 |
| Yes | 89 (3.6) | 0.96 (0.79, 1.16) | 35 (1.6) | 1.20 (0.69, 2.09) | |
| Renal impairment | |||||
| No | 2,482 (99.6) | REF | 2,187 (99.8) | REF | 0.007 |
| Yes | 11 (0.4) | 1.25 (0.86, 1.82) | 5 (0.2) | 2.36 (1.30, 4.30) | |
| Hepatic impairment | |||||
| No | 2,438 (97.8) | REF | 2,142 (97.7) | REF | 0.20 |
| Yes | 55 (2.2) | 0.93 (0.74, 1.16) | 50 (2.3) | 1.30 (0.84, 2.00) | |
| Neutropenia | |||||
| No | 2,467 (99.0) | REF | 2,135 (97.4) | REF | 0.82 |
| Yes | 26 (1.0) | 1.03 (0.76, 1.40) | 57 (2.6) | 1.12 (0.73, 1.71) | |
| Thrombocytopenia | |||||
| No | 2,480 (99.5) | REF | 2,167 (98.9) | REF | 0.81 |
| Yes | 13 (0.5) | 0.81 (0.45, 1.48) | 25 (1.1) | 0.68 (0.27, 1.74) | |
| Tumor/cancer characteristics | |||||
| Stage | |||||
| Stage I | 501 (20.1) | REF | 473 (21.6) | REF | 0.002 |
| Stage II | 1,556 (62.4) | 0.66 (0.62, 0.71) | 1,248 (56.9) | 0.85 (0.72, 1.02) | |
| Stage IIIA | 436 (17.5) | 0.45 (0.39, 0.51) | 471 (21.5) | 0.70 (0.55, 0.88) | |
| p-trend<0.001 | p-trend=0.002 | ||||
| Grade | |||||
| Grade 1 | 301 (12.1) | REF | 164 (7.5) | REF | 0.40 |
| Grade 2 | 1,039 (41.7) | 0.99 (0.89, 1.09) | 852 (38.9) | 0.84 (0.64, 1.11) | |
| Grade 3 | 1,153 (46.2) | 0.90 (0.81, 1.01) | 1,176 (53.6) | 0.84 (0.63, 1.12) | |
| p-trend=0.02 | p-trend=0.42 | ||||
| Hormone-receptor status | |||||
| ER− and PR− | 676 (27.1) | REF | 690 (31.5) | REF | 0.74 |
| ER+ and/or PR+ | 1,817 (72.9) | 1.20 (1.10, 1.30) | 1,502 (68.5) | 1.19 (0.99, 1.43) | |
| HER2 status | |||||
| HER2− | 2,104 (84.4) | REF | 2,010 (91.7) | REF | <0.001 |
| HER2+ | 389 (15.6) | 1.34 (1.23, 1.45) | 182 (8.3) | 2.21 (1.82, 2.67) | |
| Surgery | |||||
| Breast conserving surgery | 1,245 (49.9) | REF | 1,222 (55.7) | REF | 0.60 |
| Mastectomy | 1,248 (50.1) | 1.10 (1.03, 1.18) | 970 (44.3) | 1.12 (0.96, 1.30) | |
a
Fully adjusted: age, income, renal impairment, diabetes, HER2, stage, grade, hormone receptor status, surgery type, study site. Outcome is conventional regimen (as 1) versus dose dense regimen (as 0).
b
Median neighborhood household income: calculated at neighborhood level
Abbreviations: SES, socioeconomic status; BMI, body mass index; ER: estrogen receptor; PR: progesterone receptor; HER2, human epidermal growth factor receptor-2; CVD, cardiovascular disease