Breast Cancer Subtype Approximated by Estrogen Receptor, Progesterone Receptor, and HER-2 Is Associated With Local and Distant Recurrence After Breast-Conserving Therapy

Median follow-up was 70 months. The overall 5-year cumulative incidence of local recurrence was 1.8% (95% CI, 1.0 to 3.1); 0.8% (0.3, 2.2) for luminal A, 1.5% (0.2, 10) for luminal B, 8.4% (2.2, 30) for HER-2, and 7.1% (3.0, 16) for basal. On multivariable analysis (MVA) with luminal A as baseline, HER-2 (adjusted hazard ratio [AHR] = 9.2; 95% CI, 1.6 to 51; P = .012) and basal (AHR = 7.1; 95% CI, 1.6 to 31; P = .009) subtypes were associated with increased local recurrence. On MVA, luminal B (AHR = 2.9; 95% CI, 1.3 to 6.5; P = .007) and basal (AHR = 2.3; 95% CI, 1.1 to 5.2; P = .035) were associated with increased distant metastases.

Overall, the 5-year local recurrence rate after BCT was low, but varied by subtype as approximated using ER, PR, and HER-2 status. Local recurrence was particularly low for the luminal A subtype, but was less than 10% at 5 years for all subtypes. Although further follow-up is needed, these results may be useful in counseling patients about their anticipated outcome after BCT.