FRIDAY, Feb. 11, 2022 (HealthDay News) — For premenopausal women with estrogen receptor (ER)-positive breast cancer receiving ovarian suppression, use of an aromatase inhibitor rather than tamoxifen is associated with a reduced risk for recurrence, according to research published online Feb. 3 in The Lancet Oncology.

Rosie Bradley, from the University of Oxford in the United Kingdom, and colleagues conducted a meta-analysis of individual patient data from randomized trials comparing aromatase inhibitors to tamoxifen for three or five years in premenopausal women with ER-positive breast cancers receiving ovarian suppression or ablation. The trials included 7,030 women with ER-positive tumors, with a median follow-up of 8.0 years.

The researchers found that women randomly assigned to an aromatase inhibitor had a lower rate of breast cancer recurrence than those assigned to tamoxifen (rate ratio [RR], 0.79). The main benefit was in years 0 to 4 (RR, 0.68), with an absolute reduction of 3.2 percent in the five-year recurrence risk (6.9 versus 10.1 percent). In years 5 to 9 or beyond year 10, there was no further benefit or loss of benefit. The risk for distant recurrence was also reduced with aromatase inhibitors (RR, 0.83). Between treatments, there were no significant differences seen in breast cancer mortality, death without recurrence, or all-cause mortality. More bone fractures occurred with aromatase inhibitors than tamoxifen (RR, 1.27).

“Although this meta-analysis found no difference in breast cancer or all-cause mortality between the two treatment groups, this lack of difference might be explained by the limited duration of follow-up,” the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

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