- Human epidermal growth factor receptor 2 (HER2)-positive breast cancer
- HER2-negative cancer or hormone-receptive breast cancer (estrogen-receptive or progesterone receptive cancer)
The HER2 protein is a type of a receptor found on the surface of the breast cells. It is involved in the normal growth of the breast cells. There is a HER2 gene that controls the production of HER2. When there is a defect in this gene, it makes more than the required copies of HER2. Excess of HER2 results in overgrowth of the abnormal breast cells, giving rise to HER2-positive cancer.
When you have been diagnosed with breast cancer, doctors check if you have HER2-positive or HER2-negative breast cancer. The type of breast cancer is diagnosed based on tests that check for the presence of HER2 protein in the breast tissue. If the test is positive, it means you have HER2-positive cancer, and if the test results are negative, you may have HER2-negative cancer, which may be either estrogen-positive or progesterone-positive cancer. Out of all breast cancer cases, 80% are estrogen-positive ones.
Knowing the type of breast cancer you have is essential in deciding the type of treatment for you—whether you need treatments targeted at the HER2 protein, estrogen, or progesterone.
What foods to avoid if you have estrogen-positive breast cancer?
Research shows that among breast cancer cases,
- only 5-10% were because of genetic defects.
- 90-95% were attributable to environmental and lifestyle factors such as diet. Out of these,
- Sugary foods:
- Added sugars in foods and drinks (such as in fruit juices and high-fructose corn syrup)
- White bread
- White pasta
- White rice
- White flour-containing baked products
- Saturated fats (increases your low-density lipoprotein (LDL) and helps grow breast cancer cells)
- Deep-fried foods
- Non-dairy creamers
- Packaged cookies and crackers
- Cake mixes
- Processed snacks
- Red meat and chicken with skin (increases your cholesterol levels and promotes the growth of breast cancer cells)
- Alcohol (promotes the growth of breast cancer cells)
Research says that some foods play a role in slowing down the growth of cancer cells or enhancing the efficacy of cancer medications. These include:
- Citrus fruits such as:
- Vegetables and herbs:
- Good fats (especially those that contain omega-3 fatty acids):
- Lean proteins:
- Adequate fiber intake (25-30 g daily)
- Adequate fiber intake
Despite weak estrogen-like action, soya and flax seeds help make tumor cells less aggressive as per some research. However, talk to your oncologist before you start soya or flaxseed products as diet supplementation.
Please note that these foods are not a replacement for your regular cancer treatment.
Along with controlling dietary factors, pay attention to exercising that plays an equivalent role in keeping weight under control. Obesity also increases your risk of breast cancer. If you want a special dietary plan tailored to your needs, consider consulting a certified nutritionist.
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Bao PP, Shu XO, Zheng Y, et al. Fruit, vegetable, and animal food intake and breast cancer risk by hormone receptor status. Nutr Cancer. 2012;64(6):806-819.
Guinter MA, McLain AC, Merchant AT, et al. A dietary pattern based on estrogen metabolism is associated with breast cancer risk in a prospective cohort of postmenopausal women. Int J Cancer. 2018;143(3):580-590.
Nutrition & Breast Cancer. https://cancer.ucsf.edu/sites/cancer.ucsf.edu/files/_docs/crc/nutrition_breast.pdf