Breast cancer starts in the breast tissue, starts growing uncontrollably, and usually becomes a solid tumor. In the United States, it is the second most common type of cancer in women and it only rarely occurs in men. Most often, breast cancer starts in the ducts, which are the tubes that carry breast milk to the nipple.^[1]

Some symptoms of breast cancer include:^[1]

• A new lump or thickening in or around the breast or armpit (note that often breast lumps are found to be non-cancerous)
• Pain in breast area or change in breast shape/size
• Breast skin dimpling or puckering, or a nipple turned inward
• Unusual nipple discharge (e.g. bloody, sudden, one sided) other than breast milk
• Scaly, red, or swollen skin in the nipple area or the breast

Breast cancer is suspected after a clinical breast exam which is positive for lumps or unusual changes with the breasts and armpits. A diagnosis is made after extensive testing including imaging tests (mammogram, ultrasound), breast biopsy, blood chemistry tests, and genetic tests. After a diagnosis is made, further testing is done to characterize the breast cancer. For example, tests for progesterone/estrogen receptor density and cancer metastasis are completed to personalize treatment options.^[1]

Medical treatments usually include surgery to remove the tumor and some breast tissue around it (lumpectomy), surgery to remove the whole breast (mastectomy), radiation treatment, and/or chemotherapy. Other common treatments for breast cancer include hormone therapy, targeted therapy, and immunotherapy.^[1]

Research on the use of dietary supplements for breast cancer is limited. Some supplements assessed for benefit in breast cancer include vitamin C, vitamin D, beta-carotene, and turkey tail (Coriolus versicolor).^[2] There is also interest in supplements like EPA and DHA for reducing the side effects of breast cancer chemotherapy.^[3]

A nutritious and balanced diet high in vegetables, fruit, nuts, unrefined cereals, and low in saturated fats and red meat has been linked with increased survival in those diagnosed with breast cancer and better tolerability of medical treatments for breast cancer. Certain chemotherapy drugs cause depletion of certain nutrients from the body, therefore a nutrient rich and balanced diet is imperative to prevent deficiencies.^[3] Diets such as the Mediterranean Diet, the DASH diet, anti-inflammatory diets have been associated with improved outcomes and quality of life in patients treated for breast cancer.^[4]

From the preventative standpoint, lifestyle interventions such as adequate exercise, limiting alcohol, limiting hormone therapy, and breastfeeding have been associated with reduced risk for developing breast cancer.^[1] Some evidence suggests that mind-body modalities such as yoga and mindfulness can improve quality of life and mood disturbances in patients receiving chemotherapy for breast cancer.^[5][6]

Although the exact cause is not known, breast cancer typically starts with genetic material (DNA) mutations which are either inherited or developed from lifestyle and/or environment. Certain factors that are linked to increased risk of breast cancer include: older age, history of breast disease, BRCA1 and BRCA2 genes, obesity and alcohol use. Also, increased exposure to estrogen increases the risk of breast cancer and occurs in conditions such as early menstruation, late menopause, hormone therapy for menopause, and either never giving birth or giving birth at an older age.^[1]