Because the efficacy of tamoxifen vs anastrozole is similar for women older than 60 years of age with ductal carcinoma in situ (DCIS) treated with lumpectomy plus radiotherapy, drug-associated symptoms and risk for serious adverse events should drive treatment decisions, a new study published online ahead of print in the journal The Lancet has shown..1

The NSABP B-35 trial evaluated the efficacy and safety of anastrozole compared with tamoxifen for reducing disease recurrence of breast cancer in postmenopausal women with DCIS. This analysis focused on the impact of these aromatase inhibitors on symptoms and quality of life.

For the study, researchers enrolled 3104 patients with hormone receptor-positive DCIS treated with lumpectomy with clear resection margins and whole breast irradiation, of which 1193 were included in this analysis. Participants were randomly assigned to receive tamoxifen 20 mg orally daily or anastrozole 1 mg orally daily for 5 years. Patients completed questionnaires at baseline and every 6 months for 6 years.

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Results showed that there were no significant differences between treatment arms for physical health scores (P = .20), mental health scores (P = .38), energy and fatigue (P = .86), sexual functioning (P = .56), or symptoms of depression (P = .46) over 5 years; however, vasomotor symptoms (P = .011), difficulty with bladder control (P = .0002), and gynecological symptoms (P < .0001) were significantly worse with tamoxifen than with anastrozole. On the other hand, musculoskeletal pain (P = .0006) and vaginal symptoms (P = .035) were significantly more severe in the anastrozole arm.

Researchers found that age less than 60 years was significantly associated with more severe vasomotor symptoms (P = .0006), vaginal symptoms (P < .0001), weight problems (P < .0001), and gynecological symptoms (P = .014) compared with age 60 years or older.

“Given the similar efficacy of tamoxifen and anastrozole for women older than age 60 years, decisions about treatment should be informed by the risk for serious adverse health effects and the symptoms associated with each drug,” the investigators concluded.

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“For women younger than 60 years old, treatment decisions might be driven by efficacy (favoring anastrozole); however, if the side effects of anastrozole are intolerable, then switching to tamoxifen is a good alternative.”


  1. Ganz PA, Cecchini RS, Julian TB, et al. Patient-reported outcomes with anastrozole versus tamoxifen for postmenopausal patients with ductal carcinoma in situ treated with lumpectomy plus radiotherapy (NSABP B-35): a randomised, double-blind, phase 3 clinical trial [published online ahead of print December 10, 2015]. Lancet. doi: 10.1016/S0140-6736(15)01169-1.