Prognosis and management of patients with node-negative invasive breast carcinoma that is 1 cm or smaller in size (stage 1; T1a,bN0M0): a review of the literature.

PURPOSE: Mammographic screening has led to an increase in the number of small, node-negative breast cancers being diagnosed. Node-negative breast cancers that are < or = 1 cm are stage T1a,bN0M0. Controversy surrounds the prognosis of these patients with locoregional therapy only and the need for adjuvant systemic therapy.
METHODS: We performed a comprehensive review of the literature describing outcome and prognostic factors in stage T1a,bN0M0 breast cancer. We also reviewed current guidelines for systemic therapy in these patients.
RESULTS: Early studies reported 10-year relapse-free survival (RFS) rates higher than 90% without adjuvant systemic therapy, but some more recent data suggest inferior outcomes. High tumor grade is the most consistent factor associated with poor prognosis. Other adverse prognostic factors are younger age, lymphovascular invasion (LVI), high Ki-67, and larger tumors within the T1a,b subgroup. Patients with high-grade tumors and/or LVI may have 10-year RFS rates of less than 75% in the absence of systemic therapy. The prognostic significance of hormone receptor status is unclear. Current guidelines for the systemic management of early-stage breast cancer differ when applied to stage T1a,bN0M0, reflecting the controversial nature of the issue.
CONCLUSION: Adjuvant systemic therapy is advisable for most patients with stage T1a,bN0M0 breast cancer who have grade 3 tumors and/or LVI. Other T1a,bN0M0 cases should be considered for systemic therapy based on clinicopathologic factors with known prognostic significance and assessment of the risk-benefit ratio. More reliable tools are needed to assess the prognosis of patients with stage T1a,bN0M0 breast cancer and their potential to benefit from specific therapeutic agents.