Predictive value of breast cancer molecular subtypes in Chinese patients with four or more positive nodes after postmastectomy radiotherapy.

The molecular subtypes of breast cancer based on status of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (Her2) expression are associated with markedly different clinical outcomes. We retrospectively analyzed 774 breast cancer patients with four or more positive nodes, who underwent mastectomy between March 1999 and December 2007. Treatment with postmastectomy radiotherapy (PMRT) reduced the rates of locoregional recurrence-free survival (LRFS; 6.7% vs. 26.6%), distant metastasis-free survival (DMFS; 26.9% vs. 50.0%), and mortality (24.4% vs. 45.3%) for luminal-A subtypes (ER+ or PR+, Her2-) and reduced LRFS (12.1% vs. 27.5%) for the luminal-B subtype (ER+ or PR+, Her2+) compared with patients not receiving PMRT. However, PMRT did not affect the endpoints for the Her2-enriched or basal subtypes. Thus, understanding the differences in patterns of relapse between the different subtypes of breast cancer may enable targeted adjuvant therapy and improved surveillance decisions.