In Pink October dedicated to breast cancer awareness, questions arise, including: Does soy milk cause breast cancer? What are the symptoms of the disease? Where did the idea for Pink October come from? The answers and more are in this comprehensive report.
Breast Cancer Awareness Month dates back to October 1985, when the first organized movement to draw attention to breast cancer risks took place in the United States, according to Hocking College.
The aim is to raise awareness of breast cancer and share information about it, in addition to providing detection and examination services related to it. Globally the idea has been promoted and its application expanded in many countries for breast cancer awareness.
Do soy milk and tofu lead to breast cancer?
Studies show that a lifelong diet rich in soy foods reduces the risk of breast cancer in women, says dietitian Katherine Zeratsky, of the Mayo Clinic. This protective effect is less pronounced for women who eat less soy or who start eating soy later in life. Soy contains protein, isoflavones, and fiber, all of which provide health benefits.
Zyratsky adds that soy foods were thought to increase the risk of breast cancer. However, eating a moderate amount of soy foods does not increase the risk of breast cancer or other types of cancer. A moderate amount is one to two servings a day of whole soy foods, such as tofu and soy milk.
One serving of soy milk is one cup (240 milliliters), and one serving of tofu is about 85 grams.
So, where did the idea that soybeans increase the risk of breast cancer come from? Zyratsky explains that the isoflavones in soybeans are plant estrogens. High levels of estrogen have been linked to an increased risk of breast cancer. However, soy food sources do not contain high enough levels of isoflavones to increase the risk of breast cancer.
On the other hand, soy or isoflavones supplements generally contain higher levels of isoflavones. Some studies have suggested a link between soy or isoflavone supplements and an increased risk of breast cancer in women with a family or personal history of breast cancer or thyroid problems. Talk to your doctor or dietitian before taking supplements, and never take them without consulting your doctor.
What does the American Cancer Society say about soy and breast cancer?
According to the association, so far the evidence does not indicate any risks from eating soy, and the health benefits appear to outweigh any potential risks. In fact, there is growing evidence that eating traditional soy foods such as tofu, tempeh, edamame, miso and soy milk may reduce the risk of breast cancer, especially among Asian women.
The association adds that soy foods are excellent sources of protein, especially when they replace other, less healthy foods such as animal fats and red or processed meat. Soy foods have been linked to lower rates of heart disease and may help lower cholesterol.
According to Margie McCullough, strategic director of nutritional epidemiology for the American Cancer Society, soy foods are healthy and safe. But she advises against taking soy supplements – which contain much higher concentrations of isoflavones than food – until more research is done.
The association adds that some misunderstanding comes from the fact that human studies and animal studies may show different results. In some animal studies, rodents exposed to high doses of compounds in soybeans called isoflavones showed an increased risk of breast cancer. This is thought to be because the isoflavones in soy can act like estrogen in the body, and excess estrogen has been linked to certain types of breast cancer.
But rodents process soy differently than humans do, and humans have not shown the same results. Also, doses of isoflavones in animal studies are much higher than in humans. In fact, in human studies it appears that the estrogenic effects of soy either have no effect at all or reduce the risk of breast cancer especially in Asian countries.
The World Health Organization says breast cancer is the most common type of cancer, with more than 2.2 million cases in 2020.
About 1 in 12 women will develop breast cancer in their lifetime. Breast cancer is the number one cause of cancer death among women, and nearly 685,000 women died from it in 2020.
What is breast cancer?
Breast cancer is an abnormal growth of cells, and the WHO says that breast cancer originates in the cells lining (the epithelium) of the ducts (85%) or the lobules (15%) of the glandular breast tissue. Initially, the cancerous growth is confined to the cannula or lobule (“in situ”) and generally does not cause symptoms.
Over time, these in situ (stage 0) cancers may develop and invade surrounding breast tissue (invasive breast cancer) and then spread to nearby lymph nodes (near tumor metastases) or to other organs in the body (distant metastases). If a woman dies of breast cancer, this is attributed to widespread metastases.
Breast cancer treatment can be very effective, especially when the disease is detected early. Breast cancer treatment often involves a combination of surgical removal, radiotherapy and medication.
What are the symptoms of breast cancer?
Breast cancer usually appears as a painless lump or thickening of the breast. It is important that women who find an abnormal breast lump consult a health professional without delay for more than a month or two even when they do not feel any associated pain. Seeking medical attention at the first sign of a possible symptom allows for more successful treatment, according to the World Health Organization.
In general, symptoms of breast cancer include:
- A lump or thickening in the breast.
- A change in the size, shape, or appearance of the breast.
- Dimpling, redness, impression or other change in the skin.
- A change in the appearance of the nipple or a change in the skin around the nipple (areola).
- Abnormal nipple discharge.