Women with Low-Risk Breast Cancer Could Avoid Overtreatment

Tumor specimens from all patients were evaluated by means of 21-gene (Oncotype Dx) assay to analyze tumor specimens and determine disease risk, as derived from prior studies that suggest recurrence risk as high as 10% at 5 years among women with a score of 11, and as high as 20% for women with a risk score of 25.

Accordingly, women who had a risk score of 0–10 (range 0–100) received endocrine therapy alone. Women with scores over 26 received adjuvant chemotherapy plus hormonal therapy; those with intermediate scores of 11–25 were randomized to chemotherapy plus endocrine therapy, or endocrine therapy alone. The primary endpoint was survival free of invasive cancer, including local, regional, distant, or contralateral breast cancer recurrence; second non-breast invasive cancer; or death without evidence of recurrence.

The results showed that 1,626 women had a risk score of 10 or less, and all but 6 of them received endocrine therapy without chemotherapy, with a 5-year freedom from invasive recurrence at 98.7%. The risk of metastatic recurrence was less than one percent, and 98% of the women remained alive at five years, with only tumor grade demonstrating a significant association to freedom from recurrence. The results were presented at the European Cancer Congress, held during September 2015 in Vienna (Austria).

“About 85% of the patients would be expected to remain free of recurrence after 5 years if they received only endocrine therapy. The addition of chemotherapy would lead to a reduction in relative risk of 30% or an absolute reduction of 5%,” said lead author Joseph Sparano, MD. “Many patients with estrogen receptor-positive breast cancer would therefore be overtreated with chemotherapy on the basis of clinicopathologic features alone, since most would have been adequately treated with endocrine therapy alone.”

Adjuvant chemotherapy has been shown to reduce the risk of recurrence across a broad population of breast cancer patients, including those with a low risk of recurrence on the basis of anatomic and clinical features. In 2001 a consensus panel convened by the US National Institutes of Health (NIH; Bethesda, MD, USA) concluded that adjuvant combination chemotherapy should be recommended to the majority of women with localized breast cancer regardless of lymph node, menopausal, or hormone receptor status.

Related Links:
Albert Einstein College of Medicine
US National Institutes of Health