The purpose of this study is to evaluate the use of advanced quantitative mass spectometry (Super SILAC) as a discovery platform to uncover novel protein biomarkers in tumor and to compare the protein profile between different subtypes of breast cancer (ER positive, HER2 positive, triple negative). A maximum of 100 breast tumor specimens will be obtained from the NUHS Tissue repository, comprising approximately equal proportion of ER positive, HER2 positive, and triple negative tumors. Samples will be analyzed using advanced Mass Spectrometry (Super SILAC) as a discovery platform to identify novel protein biomarkers that may be important in cancer. DNA and RNA will also be extracted from tumor samples for correlative analysis with the proteomics data. Genomics and proteomics data will be correlated with clinical data including treatment response and survival data. Importance of proposed research to science or medicine:Identification of tumor biomarkers may allow better prognostication, follow-up, and selection of treatment for cancer patients in the future. Potential benefits and risks: No direct benefit to the patient. Risk to the subjects is minimal as there is no direct patient contact, and analysis is done on previously donated tumor samples. Patients have previously provided consent to donate their samples for research into the NUHS Tissue Repository.

Novel tumor biomarkers that determine tumor biology, including prognosis and treatment sensitivity, may be detectable using the novel advanced quantitative mass spectromy method (Super SILAC). Different subtypes of breast cancers will have different proteomic profiles analyzed using super SILAC.

Inclusion Criteria:

• Patients with breast cancer

Tumor specimens that have been stored in the NUHS tissue repository will be retrieved