Age and survival estimates in patients who have node-negative T1ab breast cancer by breast cancer subtype.

Aim: This article evaluates the risk of recurrence for patients who have small node-negative breast cancer by age and tumor subtype.

Methods: One thousand twelve patients with a T1a,bN0 breast cancer diagnosed between 1990 and 2002 who did not receive chemotherapy or trastuzumab were included. Patients and tumor characteristics were compared using the χ(2) or Wilcoxon's rank sum tests. Survival outcomes were estimated with the Kaplan-Meier method and compared using the log-rank statistic. Cox proportional hazards models were used to determine association of breast cancer subtypes and age at diagnosis with other covariates.

Results: Median age was 51.5 years. There were 771 hormone receptor (HR)-positive, 98 HER2-positive, and 143 triple-negative breast cancers (TNBC). Six hundred ninety-three patients were > 50 years, and 33 patients were ≤ 35 years. For 5-year survival estimates, there were 118 deaths and overall survival was 94.6% (95% confidence interval [CI] = 93.2%, 96.1%). After adjusting for breast cancer subtype and other tumor characteristics, patients ≤ 35 had 2.51 (95% CI = 1.21-5.22) times greater risk of worse recurrence-free survival (RFS), and 2.60 (95% CI = 1.05-6.46) times greater risk of worse distant RFS (DRFS) compared to patients > 50 years old. Compared to patients with HR-positive disease, patients with HER2-positive breast cancer had 4.98 (95% CI = 2.91-8.53) times the risk of worse RFS and 4.70 (95% CI = 2.51-8.79) times greater risk of worse DRFS, and patients with TNBC had 2.71 (95% CI = 1.59-4.59) times greater risk of worse RFS and 2.08 (95% CI = 1.04-4.17) times greater risk of worse DRFS.

Conclusions: In this cohort, patients with T1a,bN0 breast cancer, young age and breast cancer subtype were significantly associated with RFS and DRFS.