Led by Gilda Hillman, Ph.D., professor of radiation oncology at Wayne State University, a research team had previously demonstrated that soy isoflavones, a naturally occurring compound in soybeans, increases the ability of radiation to kill cancer cells in prostate tumors. This compound is capable of blocking DNA repair mechanisms and molecular survival pathways, which are turned on by the cancer cells to survive the damage caused by radiation.
In addition, isoflavones act to reduce damage caused by radiation to normal, surrounding tissue. A clinical trial at WSU and Karmanos was able to demonstrate this by treating prostate cancer patients with radiotherapy and soy tablets.
Published in the journal Nutrition and Cancer, the patients in the trial experienced a reduction in radiation toxicity to surrounding organs; fewer challenges with incontinence and diarrhea; and better sexual organ function. Hillman’s preclinical studies in the prostate tumor model helped her design a new clinical trial.
Soy Isoflavones are capable of making cancer cells more susceptible to ionizing radiation by blocking survival pathways that are activated by radiation in cancer cells but not in normal cells. In healthy tissue, soy isoflavones can also serve as antioxidants, protecting those tissues from damaged induced by radiation.
According to Hillman, “Preliminary studies indicate that soy could cause radioprotection. It is important to show what is happening in the lung tissue.” She claims the next step is to evaluate the effects of soy isoflavones in mouse lung tumor models to determine the required conditions for maximizing tumor-killing and normal tissue-protecting outcomes during radiation therapy.
Hillman believes if the researchers succeed in addressing preclinical issues in the mouse cancer model, it is possible to design clinical protocols for non-small cell lung cancer to improve radiotherapy. She also believes this treatment could be used to improve the secondary effects of radiation, such as, improving the level of breathing in the lungs.
Once these protocols are developed, clinicians can start using soy isoflavones combined with radiation therapy in humans, a process that they believe will yield both therapeutic and economic benefits. Hillman concludes that in contrast to drugs, soy is a very safe compound. She adds it is also readily available and cheap.