Potential benefits of local radiotherapy in addition to adjuvant chemotherapy in female patients with triple-negative breast cancer in the absence of distant metastases: a SEER database analysis.

BACKGROUND: There is no consensus on the advisability of additional supplementation with local radiotherapy in non-metastatic triple-negative breast cancer (TNBC) patients. The present study is the first analysis to construct a risk-scoring model to determine prognosis for TNBC without distant metastases, with a view to identifying groups for whom local radiotherapy would be of benefit. METHODS: Cases of female patients diagnosed with non-metastatic TNBC patients who received adjuvant chemotherapy were extracted from Surveillance Epidemiology and End Results (SEER) database. Breast cancer-specific death (BCSD) was used as the primary prognostic indicator; sub-distribution hazard ratio (sHR) with 95% confidence interval (CI) was used to analyze the effect of radiotherapy with risk-stratification. Differences were considered statistically significant if P≤0.05. RESULTS: A total of 19,371 patients were enrolled. Cumulative incidence function and sub-distribution hazard function showed that year of diagnosis, race, grade, lymph node (N) stage, primary site, lymph node ratio and tumor size were all associated with the probability of cancer-specific death (P<0.05). As regards BCSD, there was no survival benefit in receiving radiotherapy for low-risk (score ≤122) patients (sHR =0.839, 95% CI: 0.69-1.02, P=0.08), but radiotherapy improved survival for medium- and high-risk (score >122) groups (medium-risk: sHR =0.801, 95% CI: 0.682-0.941, P=0.007; high-risk: sHR =0.618, 95% CI: 0.516-0.74, P<0.001). CONCLUSIONS: A novel risk scoring system was constructed based on the results of the survival nomogram to screen for medium-high risk patients for whom radiotherapy may bring additional benefit.