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Purpose: Postmastectomy radiation therapy (PMRT) can reduce locoregional recurrences (LRR) in high-risk patients, but its role in the treatment of lymph node negative (LN-) breast cancer remains unclear. The aim of this study was to identify a subgroup of T1-T2 breast cancer patients with LN- who might benefit from PMRT., Methods and Materials: We retrospectively reviewed 1,136 node-negative T1-T2 breast cancer cases treated with mastectomy without PMRT at the Massachusetts General Hospital between 1980 and 2004. We estimated cumulative incidence rates for LRR overall and in specific subgroups, and used Cox proportional hazards models to identify potential risk factors., Results: Median follow-up was 9 years. The 10-year cumulative incidence of LRR was 5.2% (95% CI: 3.9-6.7%). Chest wall was the most common (73%) site of LRR. Tumor size, margin, patient age, systemic therapy, and lymphovascular invasion (LVI) were significantly associated with LRR on multivariate analysis. These five variables were subsequently used as risk factors for stratified analysis. The 10-year cumulative incidence of LRR for patients with no risk factors was 2.0% (95% CI: 0.5-5.2%), whereas the incidence for patients with three or more risk factors was 19.7% (95% CI: 12.2-28.6%)., Conclusion: It has been suggested that patients with T1-T2N0 breast cancer who undergo mastectomy represent a favorable group for which PMRT renders little benefit. However, this study suggests that select patients with multiple risk factors including LVI, tumor size ≥2 cm, close or positive margin, age ≤50, and no systemic therapy are at higher risk of LRR and may benefit from PMRT., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Purpose: To examine the relationship between lymphovascular invasion (LVI) and regional nodal failure (RNF) in breast cancer patients with zero to three positive nodes treated with breast-conservation therapy (BCT)., Methods and Materials: The records of 1,257 breast cancer patients with zero to three positive lymph nodes were reviewed. All patients were treated with BCT at Massachusetts General Hospital from 1980 to December 2003. Lymphovascular invasion was diagnosed by hematoxylin and eosin-stained sections and in some cases supported by immunohistochemical stains. Regional nodal failure was defined as recurrence in the ipsilateral supraclavicular, axillary, or internal mammary lymph nodes. Regional nodal failure was diagnosed by clinical and/or radiologic examination., Results: The median follow-up was 8 years (range, 0.1-21 years). Lymphovascular invasion was present in 211 patients (17%). In univariate analysis, patients with LVI had a higher rate of RNF (3.32% vs. 1.15%; p = 0.02). In multivariate analysis, only tumor size, grade, and local failure were significant predictors of RNF (p = 0.049, 0.013, and 0.0001, respectively), whereas LVI did not show a significant relationship with RNF (hazard ratio = 2.07; 95% CI, 0.8-5.5; p = 0.143). The presence of LVI in the T2/3 population did not increase the risk of RNF over that for those with no LVI (p = 0.15). In addition, patients with Grade 3 tumors and positive LVI did not have a higher risk of RNF than those without LVI (p = 0.96)., Conclusion: These results suggest that LVI can not be used as a sole indicator for regional nodal irradiation in breast cancer patients with zero to three positive lymph nodes treated with BCT., (Copyright © 2010 Elsevier Inc. All rights reserved.)