Long-Term Survival Update From Secondary Analysis of Stockholm Tamoxifen Trial
Posted: Monday, September 13, 2021
Long-term survival of patients with breast cancer receiving endocrine therapy is poorly understood. In a recent study aimed to determine the impact of adjuvant tamoxifen in patients with lymph node–negative, estrogen receptor–positive/ERBB2-negative breast cancer, Anna Nordenskjöld, MD, PhD, and colleagues from Karolinska Institutet and University Hospital, Stockholm, determined that there was a significant long-term benefit from tamoxifen observed in patients with larger, lower-grade, and progesterone receptor–positive tumors. Their results were published in JAMA Network Open.
A total of 565 postmenopausal women with lymph node–negative, estrogen receptor–positive/ERBB2-negative breast cancer were selected for long-term secondary analysis. Patients were randomly assigned to receive 2 years of adjuvant tamoxifen therapy or no endocrine therapy. After 2 years, patients were further randomly assigned to receive an additional 3 years of tamoxifen or no treatment.
Overall, the results determined that tumor size (88% for T1a/b vs. 76% for T1c vs. 63% for T2 tumors) and tumor grade (81% for grade 1 vs. 77% for grade 2 vs. 65% for grade 3 tumors) were significantly associated with a long-term risk of distant recurrence. Compared with larger tumors (grade 3), patients with smaller tumors (grade 1 or 2) had a significant reduction in long-term distant recurrence–free interval.
In tamoxifen-treated patients, tumors that were larger (hazard ratio [HR] = 0.53 for T1c and HR = 0.34 for T2), of a lower grade (HR = 0.24 for grade 1 tumors and HR = 0.50 for grade 2 tumors), and progesterone receptor–positive (HR = 0.38), had a significant benefit in distant recurrence–free interval. Immunohistochemical analysis revealed a reduced distant recurrence–free interval in the group given tamoxifen who had a medium to high Ki67 expression and low Ki67 expression.
The authors concluded: “Tumor size and tumor grade are associated with long-term survival, and patients with larger tumors, lower tumor grades, and progesterone receptor–positive status experienced significant treatment benefit with receipt of tamoxifen therapy.”
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.