Table 3.
Adjusted associations between any endocrine therapy, tamoxifen or AI initiation within 12 months of breast cancer diagnosis
| Characteristic | Any endocrine therapya vs. none | Tamoxifen first vs. none | AIs first vs. none (ages ≥55) | |||
|---|---|---|---|---|---|---|
| Model 1b RR (95% CI) |
Model 2c RR (95% CI) |
Model 1b RR (95% CI) |
Model 2c RR (95% CI) |
Model 1b RR (95% CI) |
Model 2c RR (95% CI) |
|
| Total number of patients | 6329 vs. 1448 | 6329 vs. 1448 | 3105 vs. 1448 | 3105 vs. 1448 | 2746 vs 1164 | 2746 vs 1164 |
| Age at diagnosis | ||||||
| <45 | 0.96 (0.93-0.99) | 0.95 (0.91-0.98) | 1.21 (1.14-1.28) | 1.17 (1.10-1.24) | -- | -- |
| 45-<55 | 1.01 (0.99-1.03) | 1.00 (0.98-1.03) | 1.23 (1.17-1.29) | 1.20 (1.14-1.26) | -- | -- |
| 55-<65 | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| 65-<75 | 0.93 (0.91-0.96) | 0.96 (0.93-0.98) | 0.87 (0.82-0.93) | 0.90 (0.85-0.96) | 0.90 (0.87-0.94) | 0.92 (0.89-0.96) |
| ≥75 | 0.75 (0.72-0.78) | 0.81 (0.77-0.85) | 0.68 (0.62-0.73) | 0.74 (0.68-0.81) | 0.65 (0.61-0.69) | 0.70 (0.65-0.75) |
| Year of diagnosis | ||||||
| 2001-2004 | 0.94 (0.91-0.97) | 0.92 (0.89-0.95) | 1.29 (1.20-1.38) | 1.25 (1.17-1.34) | 0.56 (0.51-0.61) | 0.55 (0.50-0.60) |
| 2005-2008 | 0.97 (0.94-1.00) | 0.96 (0.93-0.99) | 1.14 (1.06-1.22) | 1.11 (1.04-1.19) | 0.87 (0.83-0.92) | 0.87 (0.82-0.91) |
| 2009-2012 | 0.99 (0.96-1.02) | 0.98 (0.95-1.01) | 1.04 (0.97-1.12) | 1.03 (0.95-1.11) | 0.95 (0.91-1.00) | 0.95 (0.91-0.99) |
| 2013-2016 | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| Race | ||||||
| White | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| Black | 0.93 (0.87-1.00) | 0.93 (0.87-1.00) | 0.91 (0.80-1.02) | 0.90 (0.80-1.02) | 0.86 (0.75-0.99) | 0.86 (0.75-0.99) |
| American Indian/Alaska Native | 1.00 (0.90-1.12) | 1.00 (0.90-1.12) | 1.05 (0.88-1.27) | 1.05 (0.89-1.25) | 1.00 (0.79-1.27) | 1.00 (0.79-1.27) |
| Asian/Pacific Islander | 1.01 (0.96-1.06) | 1.01 (0.96-1.05) | 1.06 (0.98-1.15) | 1.05 (0.97-1.14) | 1.01 (0.92-1.10) | 1.01 (0.93-1.10) |
| Other | 0.95 (0.82-1.10) | 0.96 (0.84-1.11) | 0.86 (0.65-1.13) | 0.89 (0.70-1.14) | 1.05 (0.86-1.28) | 1.03 (0.85-1.26) |
| Unknown | 0.83 (0.72-0.96) | 0.84 (0.72-0.97) | 0.78 (0.62-0.97) | 0.78 (0.62-0.98) | 0.71 (0.52-0.97) | 0.72 (0.53-0.98) |
| Stage | ||||||
| I | 0.84 (0.82-0.86) | 0.88 (0.85-0.91) | 0.81 (0.76-0.85) | 0.87 (0.81-0.92) | 0.74 (0.70-0.78) | 0.77 (0.73-0.82) |
| II | 0.98 (0.96-1.01) | 1.00 (0.97-1.02) | 1.01 (0.96-1.07) | 1.04 (0.98-1.09) | 0.94 (0.90-0.99) | 0.95 (0.91-1.01) |
| III | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| Histology | ||||||
| Ductal | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| Lobular | 1.02 (0.99-1.05) | 1.02 (0.99-1.05) | 1.04 (0.98-1.10) | 1.04 (0.98-1.10) | 1.02 (0.97-1.08) | 1.03 (0.97-1.08) |
| Mixed | 1.02 (0.98 to 1.05) | 1.02 (0.99 to 1.05) | 1.01 (0.95 to 1.07) | 1.01 (0.96 to 1.07) | 1.07 (1.01 to 1.13) | 1.07 (1.01 to 1.14) |
| Other | 0.86 (0.81 to 0.92) | 0.87 (0.82 to 0.93) | 0.83 (0.75 to 0.92) | 0.84 (0.75 to 0.93) | 0.78 (0.69 to 0.89) | 0.79 (0.70 to 0.90) |
| HR Status | ||||||
| ER+/PR+ | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| ER+/PR− | 0.96 (0.93-0.99) | 0.96 (0.93-0.99) | 0.92 (0.86-0.98) | 0.91 (0.86-0.97) | 0.96 (0.91-1.02) | 0.96 (0.91-1.01) |
| ER−/PR+ | 0.49 (0.37-0.64) | 0.48 (0.37-0.63) | 0.44 (0.31-0.63) | 0.43 (0.30-0.62) | 0.36 (0.21-0.64) | 0.36 (0.21-0.64) |
| HER2 status | ||||||
| Positive | 1.03 (1.00-1.07) | 1.02 (0.98-1.05) | 1.04 (0.97-1.12) | 1.03 (0.96-1.10) | 1.06 (1.00-1.13) | 1.04 (0.98-1.11) |
| Negative | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| Missing | 0.99 (0.96-1.01) | 0.99 (0.96-1.02) | 0.92 (0.87-0.97) | 0.93 (0.88-0.98) | 1.02 (0.97-1.07) | 1.02 (0.97-1.08) |
| Tumor size, cm | ||||||
| <1 cm | 0.87 (0.83-0.90) | 0.87 (0.84-0.91) | 0.78 (0.73-0.84) | 0.79 (0.73-0.85) | 0.84 (0.78-0.91) | 0.84 (0.78-0.90) |
| 1-<2 | 1.03 (1.01-1.06) | 1.03 (1.00-1.05) | 1.03 (0.98-1.08) | 1.02 (0.97-1.07) | 1.08 (1.03-1.14) | 1.07 (1.02-1.13) |
| 2-<5 | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| ≥5 | 1.01 (0.97-1.05) | 1.02 (0.98-1.06) | 0.98 (0.90-1.07) | 0.99 (0.91-1.07) | 1.03 (0.96-1.11) | 1.04 (0.97-1.12) |
| Missing | 0.92 (0.81-1.04) | 0.92 (0.82-1.04) | 0.88 (0.72-1.08) | 0.88 (0.72-1.07) | 0.93 (0.73-1.20) | 0.94 (0.73-1.21) |
| Grade | ||||||
| Well differentiated | 0.95 (0.92-0.98) | 0.97 (0.94-1.00) | 0.98 (0.92-1.03) | 1.01 (0.95-1.06) | 0.87 (0.83-0.92) | 0.90 (0.85-0.95) |
| Moderately differentiated | 1.03 (1.00-1.05) | 1.04 (1.02-1.07) | 1.09 (1.04-1.14) | 1.11 (1.06-1.16) | 1.01 (0.97-1.06) | 1.03 (0.98-1.07) |
| Poorly differentiated/undifferentiated | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| Surgical procedure | ||||||
| BCS | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| BCS + radiotherapy | 1.29 (1.20-1.39) | 1.29 (1.20-1.39) | 1.55 (1.35-1.78) | 1.55 (1.35-1.78) | 1.31 (1.17-1.47) | 1.31 (1.17-1.47) |
| Mastectomy | 1.26 (1.16-1.36) | 1.25 (1.16-1.35) | 1.55 (1.35-1.78) | 1.54 (1.34-1.77) | 1.24 (1.11-1.40) | 1.24 (1.10-1.40) |
| Chemotherapy | ||||||
| No | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) | 1.00 (Ref) |
| Yes | 1.09 (1.06-1.12) | 1.09 (1.06-1.11) | 1.12 (1.06-1.17) | 1.11 (1.06-1.16) | 1.09 (1.05-1.14) | 1.09 (1.05-1.14) |
Abbreviations: HR - Hormone receptor; ER - Estrogen receptor; PR – Progesterone receptor; HER2 - Human epidermal growth factor receptor 2; BCS - Breast conserving surgery (lumpectomy/partial mastectomy)
a
Includes any use of tamoxifen, letrozole, anastrozole, or exemestane within 12 months of breast cancer diagnosis
b
Adjusted for age at diagnosis (<45, 45-<55, 55-<65, 65-<75, 75+), year of diagnosis (2001-2004, 2005-2008, 2009-2012, 2013-2016), stage (I,II,III), grade (well differentiated, moderately differentiated, poorly differentiated/undifferentiated), HR status (ER+/PR+, ER+/PR−, ER−/PR+), and study site (KP CO, NW and WA)
c
Adjusted for variables in model 1 + chemotherapy (yes, no), and surgery type (BCS, BCS + radiotherapy, mastectomy)