This study examines TRPC6 in predicting and preventing chemotherapy related cardiac toxicity and heart failure in patients with breast cancer. Cardiac toxicity, changes in heart function is a well-recognized complication of certain cancer related therapies. Understanding these changes may allow early intervention against therapy-related cardiac toxicity and also identify novel therapeutic targets to protect patient long-term cardiac health. Studying samples of blood from patients with breast cancer in the laboratory may help doctors learn more about changes that occur in deoxyribonucleic acid (DNA), identify biomarkers related to cardiac toxicity, and prevent the development of therapy-induced cardiac toxicity in patients receiving chemotherapy.

PRIMARY OBJECTIVE:

I. Characterize TRPC6 risk variants for doxorubicin-related cardiotoxicity in prospectively collected samples from breast cancer patients.

OUTLINE: This is an ancillary-correlative study.

Patients undergo collection of blood samples at time of enrollment. Patients who develop cardiac toxicity may undergo additional collection of blood samples. Patients' medical records are also reviewed.

Inclusion Criteria:

• 18 years of age or older
• Any breast cancer patient initiating doxorubicin/other anthracycline and patients receiving trastuzumab without doxorubicin/anthracycline in the neoadjuvant/adjuvant setting
• An understanding of the protocol and its requirements, risks, and discomforts
• The ability and willingness to sign an informed consent
• Diagnosed with therapy related cardiotoxicity defined as; cardiomyopathy, symptomatic heart failure, asymptomatic reduced systolic function, acute coronary syndrome, myocardial infarction, critical limb ischemia, cardiac arrhythmias or myocarditis possibly related to prior cancer treatment OR completed chemotherapy with no cardiotoxicity at least two years post treatment OR patients with cancer who will be initiating systemic therapy with potentially cardiotoxic medications. This will include doxorubicin chemotherapy, or trastuzumab.
• Healthy, non-pregnant, adult subjects who weigh at least 110 pounds

Exclusion Criteria:

• Inability on the part of the patient to understand the informed consent or be compliant with the protocol
• Anemia with hemoglobin less than 8
• Patients not willing to undergo a blood draw
• Patients with stage IV or distant metastatic breast cancer

Patients with breast cancer who have previously received chemotherapy, are currently being treated with chemotherapy, or are about to be treated with chemotherapy