Extended endocrine therapy use and decision making after breast cancer diagnosis.

BACKGROUND

Adjuvant endocrine therapy is recommended to extend beyond 5 years for stage II breast cancer, with less consensus for extension in stage I. We aimed to understand use of and decision making about extended endocrine therapy.

METHODS

Women aged 20-79 years diagnosed with stage I-II breast cancer in 2014-2015 and reported to Georgia and Los Angeles County Surveillance, Epidemiology, and End Results registries were surveyed at 7 months and again at 6 years postdiagnosis (n = 2361; response rate = 60%). Women with estrogen receptor-positive and/or progesterone receptor-positive disease were asked about their decision whether to continue therapy.

RESULTS

Of 831 women, 591 had completed or were completing 5 years of endocrine therapy. Among those who had decided (n = 557), 46.9% decided to continue (39.4% stage I; 62.4% stage II). On multivariable analysis, factors associated with continuation for stage I were as follows: worry about recurrence (adjusted odds ratio [aOR] = 3.35, 95% confidence interval [CI] = 1.78 to 6.32), desire for most extensive treatment (aOR = 2.15, 95% CI = 1.1 to 4.14), and primary care physician participation (aOR = 4.30, 95% CI = 2.22 to 8.32). Side effects were inversely associated with continuation (stage I: aOR = 0.21, 95% CI = 0.11 to 0.41). Associations were similar for stage II; for stage I only, bilateral mastectomy and chemotherapy were associated with continuation. Decision to continue did not vary by race, ethnicity, or demographic factors.

CONCLUSIONS

Nearly 40% of women with stage I breast cancer and two-thirds with stage II decided to extend endocrine therapy. Decision making was influenced by patient values and varied little by stage. These results can inform physician-patient discussion about extending endocrine therapy.