Introduction: Increasing evidence suggests that molecular subtype influences locoregional recurrence (LRR) of breast cancer. Previous systematic reviews that evaluated the quantitative influence of subtype on LRR predated the use of Trastuzumab. This study assessed the impact of subtype on LRR in a contemporary treatment era.
Methods: A comprehensive search for all published studies assessing LRR according to breast cancer subtype was performed. Only studies with patients treated with Trastuzumab were included. Relevant data were extracted from each study for systematic review. Primary outcome was LRR related to breast cancer subtype.
Results: In total, 11,219 patients were identified from seven studies. Overall LRR rate was 3.44%. The lowest LRR rates were in luminal A (1.7%), and the highest rates were in triple-negative (7.4%) subtypes. There were significantly lower risks of LRR in patients with luminal A subtype compared with luminal B [odds ratio (OR) 0.54, 95% confidence interval (CI) 0.38-0.76; p < 0.0004], HER2/neu-overexpressing (OR 0.32, 95% CI 0.24-0.45; p < 0.0001) and triple-negative breast cancers (OR 0.25, 95% CI 0.19-0.32; p < 0.0001). There were significant differences in LRR between the luminal B and HER2/neu-overexpressing breast cancers (OR 0.61, 95% CI 0.41-0.89; p = 0.0145). The reduced risk in HER2/neu overexpressing compared with triple-negative breast cancers approached statistical significance (OR 0.75, 95% CI 0.55-1.03; p = 0.0933).
Conclusions: Significant variations in LRR occur across breast cancer subtypes, with lowest rates in luminal cancers and highest rates in triple-negative breast cancers. Low levels of LRR highlight advances in breast cancer management in the contemporary era.