The 21-Gene Recurrence Score Assay Improved Multidisciplinary Treatment Compliance in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer Patients: An Analysis of 2,323 Patients

Purpose: The 21-gene recurrence score (RS) can guide adjuvant chemotherapy decisions in the multidisciplinary treatment (MDT) of patients with early breast cancer. This study aimed to evaluate the influence of the 21-gene RS assay on patient' compliance with MDT and its association with disease outcomes. Methods: Patients diagnosed with pN0-1, hormone receptor-positive, human epidermal growth factor receptor-2-negative breast cancer between January 2013 and June 2019 were enrolled. A logistic regression model was used to identify parameters associated with treatment adherence. Prognostic indicators were evaluated using the Cox proportional hazard models. Results: After the assay, patients were less likely to violate the treatment plan (14.9% vs. 23.1%, p < 0.001), and higher compliance rates were observed for chemotherapy (p = 0.042), radiotherapy (p = 0.012), and endocrine therapy (p < 0.001). Multivariable analysis demonstrated that the 21-gene RS assay (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.09-1.88; p = 0.009) was independently associated with MDT compliance. Moreover, compliance with MDT was independently associated with better disease-free survival (hazard ratio, 0.43; 95% CI, 0.29-0.64; p < 0.001), regardless of the 21-gene RS assay (interaction p = 0.842). Conclusion: The 21-gene RS assay improved the MDT compliance rate in patients with early breast cancer. Adherence to MDT is associated with a better prognosis.