This research study is looking at tissue samples from women with breast cancer who were treated on clinical trial NCCTG-N9831. Studying samples of tissue from patients with cancer in the laboratory may help doctors learn more about changes that occur in DNA and identify biomarkers related to cancer. It may also help doctors predict how patients will respond to treatment.

PRIMARY OBJECTIVES:

I. To determine the association between the primary breast tumor protein expression of MYC, IGF-1R, and PTEN and disease-free survival (DFS) in patients randomized on clinical trial NCCTG-N9831.

II. To determine the association between the primary breast tumor amplification status of MYC and TOP2A and DFS in patients randomized on NCCTG-N9831.

III. To determine the association between the primary breast tumor mutation status of PIK3 and DFS in patients randomized on NCCTG-N9831.

SECONDARY OBJECTIVES:

I. To determine the association between the primary breast tumor marker protein expression/amplification/mutation status of the aforementioned markers and overall survival in patients randomized on NCCTG-N9831.

II. To investigate the predictive potential of multiple marker analyses on DFS and overall survival using multivariate analysis.

III. To determine the correlation between the protein expression and amplification status of MYC in patients randomized on NCCTG-N9831.

IV. To determine the correlation between marker protein expression/amplification/mutation status and known clinicopathological characteristics of the tumors.

Inclusion Criteria

• Diagnosed with breast cancer and treated on clinical trial NCCTG-N9831

  * Randomized to treatment

• HER-2 positive disease

• Whole tissue blocks and/or tissue microarray sections available

• Hormone receptor status:

  * ER/PR status known

• Any menopausal status

Female patients with primary HER2 positive breast cancer which received doxorubicin and cyclophosphamide (AC) followed by paclitaxel with or without trastuzumab.