Reduced risk of recurrence with ovarian suppression plus tamoxifen/exemestane

An updated analysis of 2 randomised trials – SOFT and TEXT – showed long term persistence of benefits of ovarian suppression plus endocrine therapy (exemestane or tamoxifen) versus tamoxifen alone for premenopausal women with hormone receptor (HR)-positive breast cancer.

In the SOFT (NCT00066690) trial, 3,066 premenopausal women with HR-positive early breast cancer were randomised to 5 years of adjuvant tamoxifen alone or to ovarian suppression treatment (OFS) plus either tamoxifen or the aromatase inhibitor exemestane. TEXT (NCT00066703; n=2,672) had a similar design but without a single-agent tamoxifen arm. About 2,500 women did not receive additional chemotherapy. In a previous combined analysis of these studies after 5 years of follow-up, adjuvant treatment with exemestane plus OFS was shown to outperform tamoxifen plus OFS [1]. Now, Dr Meredith Regan (Dana-Farber Cancer Institute, MA, USA) presented the updated results after a longer follow-up [2].

After 12 to 13 years of follow-up, the distant metastasis-free survival rates were 88.4% with exemestane plus OFS and 86.6% with tamoxifen plus OFS (HR 0.83; P=0.03). The overall survival rates were 90.1% versus 89.1%, a non-significant difference. Tamoxifen alone, meanwhile, led to a 12-year distant metastasis-free survival rate of 84.8% and a 12-year overall survival rate of 86.8%. Low-risk patients who received no chemotherapy had a 12-year overall survival rate exceeding 95%, regardless of the endocrine strategy, including tamoxifen alone. A subgroup analysis showed that patients younger than 35, and those who received neoadjuvant chemotherapy prior to enrolment, benefited most from OFS. Within those 2 subgroups, tamoxifen plus OFS led to a 10% absolute improvement in 12-year overall survival versus tamoxifen alone, and the exemestane plus OFS combination increased the absolute difference versus single-agent tamoxifen to 15%.

"Meaningful relative reductions in distant recurrence and death persist with longer follow-up for use of ovarian suppression with either endocrine therapy versus tamoxifen alone,” said Dr Regan. “Absolute reductions are more substantial for those at higher risk, on the order of a 10% reduction in death, emphasising appropriate selection of patients to receive ovarian suppression. Notably, for those patients with low clinical-risk features who did not receive chemotherapy, the longer follow-up continues to support the use of tamoxifen alone," concluded Dr Regan.

1. Pagani O, et al. N Engl J Med 2014;371:107–118.
2. Regan MM, et al. Randomized comparison of adjuvant aromatase inhibitor exemestane (E) plus ovarian function suppression (OFS) vs tamoxifen (T) plus OFS in premenopausal women with hormone receptor-positive (HR+) early breast cancer (BC): update of the combined TEXT and SOFT trials. GS2-05, SABCS 2021 Virtual Meeting, 7–10 December.

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Posted on 31 January, 2022