|The following article features coverage from the 2020 San Antonio Breast Cancer Symposium. Click here to read more of Cancer Therapy Advisor‘s conference coverage.|
The addition of adjuvant chemotherapy to endocrine therapy benefited premenopausal, but not postmenopausal, women with hormone receptor-positive, HER2-negative breast cancer and positive nodes, according to an interim analysis of the SWOG S1007 RxPONDER clinical trial (ClinicalTrials.gov Identifier: NCT01272037). The trial data were presented at the 2020 Virtual San Antonio Breast Cancer Symposium (SABCS).
The trial included 5083 pre- and postmenopausal women with hormone receptor-positive, HER2-negative, early-stage breast cancer and 1 to 3 positive axillary lymph nodes. Only patients with a tissue recurrence score of 25 or below were eligible. Patients were randomly assigned to receive either adjuvant endocrine therapy or chemotherapy followed by endocrine therapy.
The purpose of the trial was to determine the impact that adding chemotherapy had on invasive disease-free survival (IDFS) and whether that impact correlated with recurrence score.
However, adding chemotherapy to endocrine therapy did not affect IDFS in the overall study population (hazard ratio [HR], 0.81; 95% CI, 0.67-0.98; P =.026).
In a prespecified analysis that evaluated whether chemotherapy benefit varied by menopausal status, postmenopausal women who received chemotherapy followed by endocrine therapy did not have a reduced risk of invasive disease compared with women who received endocrine therapy alone (HR, 0.97; 95% CI, 0.78-1.22; P =.82,), or an improvement in overall survival (OS; HR, 0.96; 95% CI, 0.70-1.31; P =.79)
In contrast, premenopausal women who received chemotherapy followed by endocrine therapy had a 46% reduced risk of invasive disease compared with women who received endocrine therapy alone (HR, 0.54; 95% CI, 0.38-0.76; P =.0004). At 5 years, the IDFS was 94.2% for the chemotherapy followed by endocrine therapy group and 89% for the endocrine therapy–alone group.
An OS benefit was also seen for premenopausal women who received chemotherapy followed by endocrine therapy (HR, 0.47; 95% CI, 0.24-0.94; P =.032). At 5 years, the absolute difference in OS was 1.3% between the chemotherapy followed by endocrine therapy group and endocrine therapy–alone group (98.6% vs 97.3%).
“Postmenopausal women with 1 to 3 lymph nodes involved and a recurrence score of 0 to 25 can likely safely forgo adjuvant chemotherapy without compromising invasive disease-free survival,” concluded study presenter said Kevin Kalinsky, MD, director of the Glenn Family Breast Center at Winship Cancer Institute of Emory University in Atlanta, Georgia.
“This will save tens of thousands of women the time, expense, and potentially harmful side effects that can be associated with chemotherapy infusions.”
Read more of Cancer Therapy Advisor‘s coverage of the 2020 SABCS meeting by visiting the conference page.
Kalinsky K, Barlow WE, Meric-Bernstam F, et al. SWOG S1007: adjuvant trial randomized ER+ patients who had a recurrence score < 25 and 1-3 positive nodes to endocrine therapy (ET) versus ET + chemotherapy. Presented at: 2020 Virtual San Antonio Breast Cancer Symposium; December 8-11, 2020. Abstract GS3-00.