Age, breast cancer subtype approximation, and local recurrence after breast-conserving therapy.

PURPOSE: Prior results of breast-conserving therapy (BCT) have shown substantial rates of local recurrence (LR) in young patients with breast cancer (BC). PATIENTS AND METHODS: We studied 1,434 consecutive patients with invasive BC who received BCT from December 1997 to July 2006. Ninety-one percent received adjuvant systemic therapy; no patients received trastuzumab. Five BC subtypes were approximated: estrogen receptor (ER) or progesterone receptor (PR) positive, HER2 negative, and grades 1 to 2 (ie, luminal A); ER positive or PR positive, HER2 negative, and grade 3 (ie, luminal B); ER or PR positive, and HER2 positive (ie, luminal HER2); ER negative, PR negative, and HER2 positive (ie, HER2); and ER negative, PR negative, and HER2 negative (ie, triple negative). Actuarial rates of LR were calculated by using the Kaplan-Meier method.
RESULTS: Median follow-up was 85 months. Overall 5-year cumulative incidence of LR was 2.1% (95% CI, 1.4% to 3.0%). The 5-year cumulative incidence of LR was 5.0% (95% CI, 3.0% to 8.3%) for age quartile 23 to 46 years; 2.2% (95% CI, 1.0% to 4.6%) for ages 47 to 54 years; 0.9% (95% CI, 0.3% to 2.6%) for ages 55 to 63 years; and 0.6% (95% CI, 0.1% to 2.2%) for ages 64 to 88 years. The 5-year cumulative incidence of LR was 0.8% (95% CI, 0.4% to 1.8%) for luminal A; 2.3% (95% CI, 0.8% to 5.9%) for luminal B; 1.1% (95% CI, 0.2% 7.4%) for luminal HER2; 10.8% (95% CI, 4.6% to 24.4%) for HER2; and 6.7% (95% CI, 3.6% to 12.2%) for triple negative. On multivariable analysis, increasing age was associated with decreased risk of LR (adjusted hazard ratio, 0.97; 95% CI, 0.94 to 0.99; P = .009).
CONCLUSION: In the era of systemic therapy and BC subtyping, age remains an independent prognostic factor after BCT. However, the risk of LR for young women appears acceptably low.