Characteristics and clinical outcome of T1 breast cancer: a multicenter retrospective cohort study.

BACKGROUND

A subgroup of T1N0M0 breast cancer (BC) carries a high potential of relapse, and thus may require adjuvant systemic therapy (AST).

PATIENTS AND METHODS

Retrospective analysis of all patients with T1 BC, who underwent surgery from January 1999 to December 2009 at 13 French sites. AST was not standardized.

RESULTS

Among 8100 women operated, 5423 had T1 tumors (708 T1a, 2208 T1b and 2508 T1c 11-15 mm). T1a differed significantly from T1b tumors with respect to several parameters (lower age, more frequent negative hormonal status and positive HER2 status, less frequent lymphovascular invasion), exhibiting a mix of favorable and poor prognosis factors. Overall survival was not different between T1a, b or c tumors but recurrence-free survival was significantly higher in T1b than in T1a tumors (P = 0.001). In multivariate analysis, tumor grade, hormone therapy and lymphovascular invasion were independent prognostic factors.

CONCLUSION

Relatively poor outcome of patients with T1a tumors might be explained by a high frequency of risk factors in this subgroup (frequent negative hormone receptors and HER2 overexpression) and by a less frequent administration of AST (endocrine treatment and chemotherapy). Tumor size might not be the main determinant of prognosis in T1 BC.