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TOPLINE:

Women with high-risk estrogen receptor–positive (ER-positive), human epidermal growth factor receptor 2–negative (HER2-negative) breast cancer may benefit from extending endocrine therapy beyond the standard 5 years, new research showed.

METHODOLOGY:

• Patients with ER-positive, HER2-negative breast cancer typically receive endocrine therapy for 5 years, but some patients may benefit from an extended regimen.
• To address the issue, Japanese investigators reviewed 444 patients with ER-positive, HER2-negative breast cancer who were at a high risk for recurrence after 5 years of adjuvant endocrine therapy due to positive lymph nodes, large tumor sizes, and high tumor grades.
• The study team compared outcomes in the 166 high-risk patients who continued endocrine therapy beyond 5 years with the 278 who stopped at that point; the analysis included propensity score matching of 155 patients from each group.
• Selective ER modulators were used slightly more often than aromatase inhibitors for endocrine therapy.
• Researchers assessed distant disease-free survival as well as post-relapse survival.

TAKEAWAY:

• Among the propensity score matched patients, 10-year distant disease-free survival rates were 96.3% with extended endocrine therapy vs 86.5% with the usual 5 years of treatment (P = .00382).
• Extending endocrine therapy was associated with a 73% reduction in the risk for distant metastasis among these high-risk patients (hazard ratio [HR], 0.27; P = .0054).
• Overall, 48 patients who experienced late recurrence were included in the post-relapse survival analysis, which found post-relapse survival was significantly better in patients with distant disease-free survival at 7 years and beyond (HR, 0.24) and in patients who had a better response to first-line treatment (HR, 0.072).

IN PRACTICE:

Patients with risk factors for late recurrences, such as lymph node involvement, large tumor size, and high tumor grade "should be considered for extended endocrine therapy," while "patients without risk factors of late recurrence may not require it," the authors concluded.

SOURCE:

The work, led by Masahiro Ito of Tohoku Kosai Hospital in Sendai, Japan, was published in The Breast.

LIMITATIONS:

It was a retrospective study limited to patients from one institution in Japan. The duration of extended endocrine therapy beyond the initial 5 years was not reported.

DISCLOSURES:

There was no external funding for the work, and the authors didn't have any disclosures.

M. Alexander Otto is a physician assistant with a master's degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape Medical News. Alex is also an MIT Knight Science Journalism fellow. Email: aotto@mdedge.com