Luminal A
breast cancer can present with early, unexpected
lymph node metastasis, and sentinel lymph node biopsy has been reported false negative in some cases. We aimed to construct a
biomarker-based model that predicts
lymph node metastasis in
luminal A
breast cancer, using expression of
silent mating type information regulation 2 homolog 1 (
SIRT1) and apoptosis-related factors, which are known to be closely related. We selected tissue samples of 278 cases of
luminal A invasive
ductal carcinoma, constructed tissue microarrays, and performed immunohistochemical staining for
SIRT1 and four apoptosis-related
proteins. In constructing the best predictive model for
lymph node metastasis, six clinicopathological parameters and five molecular markers were considered. Independent factors predictive of
lymph node metastasis were pT stage (OR 1.829, p = 0.027), lymphovascular invasion (OR 4.128, p < 0.001), and decreased expression of
caspase-3 (OR 0.535, p = 0.034) and of
SIRT1 (OR 0.526, p = 0.053). A combination nuclear grade, lymphovascular invasion, increased
B-cell lymphoma 2 (Bcl-2) expression, and reduced expression of
caspase-3 and of
SIRT1 yielded the strongest predictive performance for
lymph node metastasis with an area under the curve (AUC) of 0.696. This combination was also predictive of shortened disease-free survival (73.1 vs. 67.7 months, p = 0.003). Our data support a role of
SIRT1 protein as
tumor suppressor in
luminal A
breast cancer, in association with apoptosis-related
proteins. Our model based upon a combination of these
biomarkers is expected to increase accuracy of prediction of
lymph node metastasis in
luminal A
breast cancer. This might serve as a valuable tool in determining the optimal surgical strategy in
breast cancer patients.