The main goal of the current research program is to examine the use of nutraceuticals, in particular flaxseed (FLX), in the prevention of Doxorubicin and Trastuzumab (DOX+TRZ) mediated cardiotoxicity in the clinical setting. As Manitoba continues to be one of the top FLX producers in the world, there is an increasing public awareness of the importance of the consumption of this whole grain commodity in the prevention of cancer and cardiovascular disease. In North America, approximately 1 in 8 women will develop breast cancer and will receive treatment with DOX+TRZ. Although women with breast cancer are at risk of developing heart failure due to chemotherapy, FLX has the capacity to prevent this outcome. The purpose of the CANFLAX study is to establish FLX "milk" as an effective method in preventing heart failure in women with breast cancer.

Cardiovascular toxicity is a potential short and long-term complication of anti-cancer therapy with DOX+TRZ in the breast cancer setting. Although FLX is commonly consumed in up to 30% of women with breast cancer to improve overall disease burden and survival, it is important to study whether this natural dietary agent can also reduce the cardiotoxic side effects of DOX+TRZ in the clinical setting. The investigators hypothesize that the prophylactic consumption of FLX "milk" will prevent adverse cardiovascular remodeling and improve overall functional capacity in women with breast cancer receiving DOX+TRZ therapy. The two specific aims of the CANFLAX study include: Aim 1: FLX "milk" will prevent the development of heart failure in women with early stage breast cancer (EBC) who are treated with DOX+TRZ based chemotherapy; and Aim 2: FLX "milk" will improve cardiac functional capacity in this patient population.

Inclusion Criteria:

• i) ≥18 years old;
• ii) women with newly diagnosed early stage breast cancer (Stage I-IIIA)
• iii) chemotherapy with 5 fluorouracil, epirubicin, and cyclophosphamide (FEC) or adriamycin and cyclophosphamide (AC) for 4 months

Exclusion Criteria:

• i) pre-existing diagnosis of heart failure and/or LVEF<40%
• ii) pre-existing use of anti-hypertensive agents including ACE inhibitors (ACEi) or beta blockers
• iii) planned use of any herbal/antioxidant/fatty acid/nutritional supplements at any time in the duration of the study.

The 2 products (oat fibre "milk" and flax "milk") are assigned a unique ID code.