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There have been studies that have shown a higher risk of cancer in children who had a history of childhood abuse. The key seems to be that long term stress, which abuse causes, seems to cause undue stress on the immune system. These changes, and other stress responses in the body such as cortisol levels, are believed to make the cells in the body either more susceptible to cancer or less able to fight cancer off.
Most of the studies have involved children with histories of physical or sexual abuse, as these types of abuse are easier to quantify in objective terms than emotional or verbal abuse. But there is still the possibility that the abuse caused long-term stress, which caused physiological changes in the body, that made the body more at risk for developing cancer.
Stress is one of the pathways to cancer and other chronic illnesses, which is why we're seeing counseling, mindfulness/meditation techniques, exercise and stress management, and nutritional/wellness tools, and even spirituality all being used as tools to help cope with and improve the body's ability to fight these illnesses.
Here are some articles: http://www.cbsnews.com/stories/2009/06/25/health/main5113472.shtml