Table 3.

Rate of subsequent breast cancer among survivors diagnosed between 1996 and 2006 and followed through 2008 by adjuvant hormonal treatment groups

Type	N	Person-years of exposure	Number of subsequent BCa	Rate per 1000 P-Y (95% CI)	Crude HR	95% CI	Adjusted HR1	95% CI
All women	22,850	114,892	2915	25.37 (24.46–26.31)
Tamoxifen only	6797	45,987	807	17.55 (16.36–18.80)	0.50	0.46–0.55	0.54	0.49–0.60
AI only	2939	9440	230	24.37 (21.32–27.73)	0.62	0.54–0.72	0.45	0.39–0.53
Switchers2	2542	8422	130	15.44 (12.90–18.33)	0.64	0.53–0.77	0.49	0.40–0.60
No hormones	10,572	51,044	1748	34.25 (32.66–35.89)	1.00	Reference	1.00	Reference
Women with MPR3 ≥80%	19,105	93,460	2526	27.03 (25.98–28.10)
Tamoxifen only	4388	30,897	514	16.64 (15.23–18.14)	0.46	0.42–0.51	0.49	0.43–0.54
AI only	2188	7003	162	23.13 (19.71–26.98)	0.57	0.48–0.67	0.40	0.33–0.48
Switchers2	1957	6453	102	15.81 (12.89–19.19)	0.66	0.53–0.81	0.47	0.38–0.59
No hormones	10,572	49,107	1748	35.60 (33.95–37.30)	1.00	Reference	1.00	Reference

¹Adjusted for age at diagnosis, year of diagnosis, race/ethnicity, household income, health-care visits, hospitalizations, comorbidity, stage at diagnosis, primary treatment, chemotherapy, histology, grade, tumor size, lymph nodes, ER, PR, and HER2/neu status, menopause status.

²Switched from tamoxifen to aromatase inhibitor.

³MPR, medication possession ratio.