Patterns of relapse after neoadjuvant chemotherapy in breast cancer: implications for surveillance in clinical practice.

Purpose: This study aimed to identify patterns of relapse after neoadjuvant chemotherapy (NAC) for breast cancer to refine follow-up recommendations.

Methods: Retrospective analysis on 523 breast cancer patients treated with NAC at two public hospitals in Singapore between 2000 and 2014.

Results: Majority of patients (71.9%) had locally advanced disease. Median follow-up was 55 months. 5-year recurrence rate was significantly higher in triple negative breast cancer (TNBC) than non-TNBC subtypes (38.4% vs. 29.5%; p = 0.042); 85% of recurrences involved distant sites. Among TNBC and HR (hormone receptor)-/HER2+ subtypes, 97.0% and 95.0% of relapses occurred within 3 years from diagnosis respectively while 10.6% of relapses among HR+ subgroup occurred beyond 5 years. Recurrence risk in high-grade tumours decreased with time. Stage III at diagnosis (hazard ratio = 2.94; p < 0.001), grade 3 tumours (hazard ratio = 2.87; p = 0.018), not achieving pathologic complete response (pCR) (hazard ratio = 8.77; p = 0.003) and not receiving adjuvant radiotherapy (hazard ratio = 3.19; p < 0.001) were independent predictors of inferior recurrence-free survival. Serum CA 15-3 was raised in 49% of patients upon relapse; it correlated with inferior post-relapse survival (median 11 months vs. 22 months; p = 0.019).

Conclusions: While more intensive follow-up during the first 3 years may be required for patients who do not achieve pCR, especially those with TNBC and HR-/HER2+ tumours, the benefit from blood tests such as CA 15-3 appears limited, and the benefit from intensification of surveillance remains to be addressed in prospective studies on high-risk patients.