Last Updated May 2011
Worldwide, lung cancer claims the lives of over 1.5 million each year. Despite the increasing levels of air pollution, more than 85% of the patients are long-term smokers. Also, smoking women taking hormone therapy are 50% more likely to die of lung cancer. The choice of treatment depends on the type of cancer, as small-cell lung carcinoma will respond better to radiation and chemotherapy, whereas non-small-cell lung carcinoma will require surgery. Nonetheless, lung cancer remains extremely difficult to eradicate, which is motivating medical scientists to search for alternatives or complementary treatments, such as nutritional supplements.
A Taste of Traditional Chinese Medicine. While the health benefits of soybeans have been praised in Asia since the 12th Century BC, it was brought to USA in 1765 by Samuel Bowen, a sailor who had visited China. In the 1900s, after realizing that soybean is an exceptional source of protein, the Department of Agriculture optimized its production by identifying the best strains for each farming state. Nowadays, this country produces over 200 million tons of soy annually, which is sold under various forms (milk, tofu, oil, sauce).
Did you know that Henry Ford presented a "Soybean Car"
at the Dearborn Days’ annual community festival in 1941?
Soy Products Prevent Lung Cancer. Over the past 20 years, research has demonstrated that regular consumption of soy products significantly reduces hot flashes and bone loss in postmenopausal women, and can also reduce cholesterol levels. More recently, research teams have been exploring the potential of soy for the prevention of lung cancer. In 2010, a study conducted by Dr. Matthew Schabath, at the M.D. Anderson Cancer Center, showed that smokers and non-smokers maintaining a soy-rich diet presented a 46% lower risk of developing lung cancer.
What is the Magic Ingredient? Soy contains a family of proteins named phytoestrogens because they have the capacity to bind estrogen receptors. While this may sound alarming for estrogen-related cancers (breast and ovarian cancer), their affinity is 100 times weaker than the physiological form of estrogen: 17β-estradiol. More importantly, they act as anti-estrogens by competing with 17β-estradiol for its receptor. Furthermore, isoflavones inhibit key enzymes responsible for the conversion of androgens to estrogens. Consequently, the soybean-derived phytoestrogens are considered to prevent most forms of cancer.
While phytoestrogens comprise three classes of compounds (isoflavones and coumestans and lignans), isoflavones were found largely responsible for the anti-cancer properties of soy products. The common approach to drug development is to identify which isoflavone should be targeted for therapy. However, studies conducted using cultured lung cancer cells showed that soy isoflavone pills, currently used in clinical studies, possess a more potent anti-tumor activity than pure genistein.
Soy Consumption Enhances Radiotherapy. In April 2011, Dr. Gilda Hillman from the Karmanos Cancer Institute in Detroit reported that soy isoflavones improve the success of radiotherapy for lung cancer. In a nutshell, they enhance cancer cell killing by blocking DNA repair mechanisms which are turned on by these cells during radiation. In addition, their antioxidant properties protect normal tissues against the damage of radiotherapy.
Soy isoflavones prevent cancer cell DNA repair
while protecting normal tissue.
Since the fundamental mechanism behind these compounds is the selective targeting of cancer cells’ ability to repair, daily intake of mixed phytoestrogens is expected to prevent the development of cancer in healthy individuals.
Anti-Cancer Properties of Soy Extending Beyond Isoflavones. How many times have we been told that a healthy diet rich in fruits and vegetables reduces the risk of cancer? In fact, vegetables (broccoli, spinach and carrots) also contain isoflavones, but in much lower concentration than soy products. Furthermore, we are discovering other compounds in soy which stimulate the selective destruction of cancer cells. For instance, soy-derived serine protease inhibitors are currently tested for the treatment of skin cancer. For these reasons, multivitamins cannot substitute for a balanced diet, including soy and vegetables.
Guidelines for the Use of Soy in Cancer Treatment. In certain patients, excess soy consumption may cause erectile dysfunction, but this condition is fully reversible. For this reason, male cancer patients encouraged to increase their soy intake during radiotherapy should be monitored to maintain normal blood levels of testosterone.
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