Prognostic Analysis of Survival in Small Breast Cancers

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Abstract
Background: Routine axillary dissection in patients with invasive small breast cancer remains controversial. We previously reported a model for predicting nodal involvement in patients with T1a or T1b breast cancer that may guide the practice of selective nodal dissection. The objective of this study was to determine whether the prognosticators that predict nodal metastases also predict survival. Study Design: This study is a retrospective review of 2,153 women with small invasive breast cancer (≤ 1 cm) diagnosed between January 1984 and December 1995. Cases were identified from a statewide tumor registry, the Hospital Association of Rhode Island, and the tumor registry at Baystate Medical Center in Massachusetts. The impact on survival of patient age (≤40 versus >40 years), nodal status (positive versus negative), tumor size (T1a versus T1b), and tumor grade (1 versus 2 or 3) were analyzed. Breast cancer-specific survival (BCSS) was analyzed using the Kaplan-Meier method and the proportional hazards regression method. Results: There were 388 patients with tumors 0.5 cm or less (T1a) and 1,765 with tumors 0.6–1.0 cm (T1b). Nodal status was known in 68% of cases (1,461 of 2,153), and tumor grade was recorded in 42% of cases (902 of 2,153). In univariate analysis, age, grade, and nodal status were significant in their association with BCSS. Tumor size did not influence BCSS among patients with small invasive tumors. Women older than 40 years had superior survival compared with younger women (93% versus 78% at 5 years; p = 0.01). Similarly, women with low grade (1) tumors did better than those with higher grade (2 or 3) tumors (98% versus 88% at 5 years; p = 0.03). The 5-year BCSS was 96% versus 78% for node-negative versus node-positive disease, and the 10-year BCSS was 91% versus 62% (p = 0.001). In the multivariate analysis, age and nodal status remained firmly associated with survival, although grade lost its significance. Conclusions: Small tumor size does not affect survival. Although risk profiles for nodal involvement can be constructed to help guide the practice of selective axillary lymphadenectomy in patients with small invasive breast cancers, these factors cannot serve as a surrogate to nodal status in establishing patient prognosis. Nodal status remains the most powerful determinant of survival in breast cancer patients, even those with very small tumors.