Endocrine Treatment Toxicity in Breast Cancer: A Good Thing?

Specific adverse effects were associated with treatment benefit, but further confirmation is needed.

Recent studies have shown that in postmenopausal women with hormone-receptor–positive breast cancer, the benefits of adjuvant endocrine therapy seem to be associated with the adverse effects of the treatment (e.g., Lancet Oncol 2008; 9:1143).

To examine this association further, investigators conducted a phase III, multinational, open-label, randomized study of 9766 postmenopausal women with estrogen-receptor–positive or progesterone-receptor–positive breast cancer who were eligible for adjuvant endocrine treatment. Patients received either the aromatase inhibitor (AI) exemestane (25 mg daily for 5 years) or tamoxifen (20 mg daily for 2.5–3 years), followed by exemestane (25 mg daily for 2.5–2 years; sequential regimen).

Patients who reported vasomotor symptoms during the first year of treatment achieved longer disease-free survival (DFS) and longer overall survival (OS) than those who did not experience those symptoms. Women who reported musculoskeletal symptoms also achieved superior DFS but not OS. These findings were independent of endocrine therapy assignment.

CITATION(S):

Fontein DBY et al. Specific adverse events predict survival benefit in patients treated with tamoxifen or aromatase inhibitors: An international tamoxifen exemestane adjuvant multinational trial analysis. J Clin Oncol 2013 Apr 22; [e-pub ahead of print].