Analysis of Risk of Recurrence by Subtype in ≤ 1-cm Breast Tumors

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with higher recurrence rates than other breast cancer subtypes. Increasing numbers of women are being diagnosed with early-stage breast cancer because of improvements in screening mammography. TNBC is known to be highly sensitive to chemotherapy; however, the benefit of adjuvant chemotherapy among women with ≤ 1-cm, lymph node-negative TNBC is unknown.

We evaluated the recurrence rates and recurrence-free survival of 437 women diagnosed with stage T1a-T1bN0 breast cancer from 1997 to 2009 at 2 institutions, with a median follow-up time of 6.2 years. Furthermore, we examined the treatment regimens of these women and evaluated the association of adjuvant chemotherapy with recurrence-free survival.

Chemotherapy was administered more often to younger women and to women with high-grade, human epidermal growth factor receptor 2-positive or TNBC. Recurrence-free survival did not differ significantly between TNBC and estrogen receptor-positive breast cancer (hazard ratio [HR], 0.33; 95% confidence interval [CI], 0.10-1.04; P = .058). After appropriate adjustments, no significant differences were detected in recurrence-free survival between the women who had received chemotherapy and those who had not among the women with TNBC (P = .132) or within any of the breast cancer subtypes (HR, 0.6; 95% CI, 0.2-1.9; P = .392).

Prospective trials of this subcentimeter node-negative breast cancer population are warranted to guide adjuvant chemotherapy decisions.