Specific adverse events predict survival benefit in patients treated with tamoxifen or aromatase inhibitors: an international tamoxifen exemestane adjuvant multinational trial analysis

PURPOSE

Specific adverse events (AEs) associated with endocrine therapy and related to depletion or blocking of circulating estrogens may be related to treatment efficacy. We investigated the relationship between survival outcomes and specific AEs including vasomotor symptoms (VMSs), musculoskeletal adverse events (MSAEs), and vulvovaginal symptoms (VVSs) in postmenopausal patients with breast cancer participating in the international Tamoxifen Exemestane Adjuvant Multinational (TEAM) trial.

PATIENTS AND METHODS

Primary efficacy end points were disease-free survival (DFS), overall survival (OS), and distant metastases (DM). VMSs, MSAEs, and VVSs arising in the first year of endocrine treatment were considered. Patients who did not start or who discontinued their allocated therapy and/or had an event (recurrence/death) within 1 year after randomization were excluded. Landmark analyses and time-dependent multivariate Cox proportional hazards models assessed survival differences up to 5 years from the start of treatment.

RESULTS

A total of 9,325 patients were included. Patients with specific AEs (v nonspecific or no AEs) had better DFS and OS (multivariate hazard ratio [HR] for DFS: VMSs, 0.731 [95% CI, 0.618 to 0.866]; MSAEs, 0.826 [95% CI, 0.694 to 0.982]; VVSs, 0.769 [95% CI, 0.585 to 1.01]; multivariate HR for OS: VMSs, 0.583 [95% CI, 0.424 to 0.803]; MSAEs, 0.811 [95% CI, 0.654 to 1.005]; VVSs, 0.570 [95% CI, 0.391 to 0.831]) and fewer DM (VMSs, 0.813 [95% CI, 0.664 to 0.996]; MSAEs, 0.749 [95% CI, 0.601 to 0.934]; VVSs, 0.687 [95% CI, 0.436 to 1.085]) than patients not reporting these symptoms. Increasing numbers of specific AEs were also associated with better survival outcomes. Outcomes were unrelated to treatment allocation.

CONCLUSION

Certain specific AEs are associated with superior survival outcomes and may therefore be useful in predicting treatment responses in patients with breast cancer treated with endocrine therapy.

Managing the side effects of oral aromatase inhibitors

SUMMARY Aromatase inhibitors (AIs) are increasingly being used to treat postmenopausal estrogen receptor-positive breast cancer. In the short term they enhance or induce menopausal symptoms that compromise AI adherence, while in the long-term they adversely affect bone and probably also cardiovascular health, although this is mainly when compared to tamoxifen, which is cardioprotective. The distinct decrease in estrogen levels following AI administration is believed to be the main reason for the emergence of these side effects, although exact mechanisms remain to be elucidated. As such, management strategies to meet these AI-induced toxicities are still mainly symptomatic. In this review, current treatment options and promising new modalities under research will be discussed.