Soy isoflavones reduce toxicity of radiation therapy

Lung cancer is the leading cause of cancer deaths in most countries. Epidemiological studies demonstrate that high soy isoflavones intake may have beneficial effect in non-smoking women. Lung cancer patients are often treated with radiation therapy, but this therapy is limited by radiation-induced pneumonitis.

Study results

Hillman and co-workers at the Wayne State University School of Medicine, Detroit, previously investigated the effects of soy isoflavones on prostate cancer cells during radiation therapy. They found that prostate cancer patients showed reduced radiation toxicity in surrounding organs when treated with soy isoflavones. Now they investigated the possible protective role of soy isoflavones on lung cancer cells. Human lung cancer cells (from non-small cell lung carcinoma) were injected in mice to induce the formation of lung tumor nodules. Treatment with soy isoflavones (1 mg per day for 30 days) resulted in the formation of smaller tumor nodules and decreased inflammation, hemorrhage and fibrosis.

Hillman concluded that soy isoflavones stimulate the destruction of lung tumor nodules by radiation and also reduce radiation injury to normal tissue. It is well established that good nutrition important for recovering from the side effects of radiation therapy. Including soy isoflavones in this diet may further improve the results of radiation therapy in patients with non-small cell lung carcinoma.


Hillman et al. Soy isoflavones radiosensitize lung cancer while mitigating normal tissue injury. Radiother Oncol. 2011 Nov 11.