Impacts of Tumor Stage at Diagnosis and Adjuvant Therapy on Long-Term Survival Outcomes in Patients With Triple-Negative Breast Cancer Achieving Pathologic Complete Response After Neoadjuvant Chemotherapy

Abstract

Background: It remains unknown whether the tumor stage at initial diagnosis and adjuvant treatments had any impacts on the long-term survival outcomes of patients with triple-negative breast cancer (TNBC) achieving pathologic complete response (pCR) following neoadjuvant chemotherapy (NACT).

Methods: Clinical stage II-III patients with TNBC who achieved pCR after NACT were identified from the Surveillance, Epidemiology, and End Results (SEER) program (SEER cohort) and the National Clinical Research Center for Cancer (Tianjin) in China (TMUCIH cohort). Survival analyses were conducted based on tumor stages and the types of adjuvant treatment received by the patients. The outcomes of interest were overall survival (OS) and breast cancer-specific survival (BCSS).

Results: The TMUCIH cohort comprised 178 patients with a median follow-up of 55.5 months. Two and 3 patients experienced BCSS and OS events, respectively. The SEER cohort included 1218 patients with a median follow-up of 65.5 months, where 53 and 78 patients experienced BCSS and OS events, respectively. Patients diagnosed with stage III disease had significantly higher hazards of death compared to stage II disease (OS: hazard ratio [HR], 3.34; 95% confidence interval [CI], 1.84-6.07; P < .001; BCSS: HR, 2.86; 95% CI, 1.38-5.92; P < .001). Adjuvant systemic and radiation therapy did not confer additional benefits to OS and BCSS.

Conclusion: Tumor stage at initial diagnosis remains an independent predictor of long-term survival outcomes in patients with TNBC achieving pCR after NACT. Postoperative adjuvant chemotherapy and radiation therapy do not appear to provide additional benefit to their long-term prognosis.

Keywords: Adjuvant Radiation therapy; Adjuvant chemotherapy; Pathologic complete remission; Survival; TNBC.