Trends in Adjuvant Chemotherapy Use in Endocrine-Sensitive, HER-2 Negative Breast Cancer, With 1 to 3 Positive Nodes: A Single-Centre Study

Background: There is a tendency to decrease the intensity of breast cancer treatments, e.g. omitting adjuvant chemotherapy in endocrine-sensitive and HER-2 negative patients. The purpose of this study was to analyse changes in the frequency of the indication of adjuvant chemotherapy and the differences in survival over time for this subtype of breast cancer, with 1–3 positive nodes. Methods: The study was based on descriptive, observational, retrospective, single-institution research between 2004–10 and 2011–18, on endocrine-sensitive, HER-2 negative breast cancer, stage pN1 (1–3 nodes). The analytical tests carried out for a comparison of the frequency of chemotherapy use the chi-square test with Fisher's exact test. Survival data in both periods are presented. Results: A total of 236 patients were included, 66 for the period 2004–10, and 170 for 2011–18. More patients were treated with hormone therapy alone in 2011–18: hormone therapy alone 10/66 (15.20%) for 2004–10, and 83/169 (49.10%) for 2011–18; chemotherapy-hormone therapy 56/66 (84.80%) for 2004–10, and 86/169 (50.90%) for 2011–18 (P = 0.0001). For 2004–10, the 5-year overall survival probability was 100%. For 2011–18 it was 98.20% (95% CI 95.65–100). For 2004-10, 5-year disease free survival (DFS) was 96.9% (95% CI 92.7–101). For 2011–18 it was 87.7% (95% CI 81.8–93.5) (P=0,040). For 2004–10 the 5 year distant relapse free interval was 96.9% (95% CI 92.5–101.2). For 2011–18 it was 93% (95% CI 88.1–97.9) (P=0.312). Conclusion: A decrease in the indication of adjuvant chemotherapy according to the clinical risk is confirmed in endocrine-sensitive, HER-2 negative breast cancer, with 1-3 positive nodes, over the period 2011–18 compared to 2004–10. Based on the results, 5-year DFS is slightly worse in the 2011–18 period.