Monday, September 6, 2010

Child abuse, stress, cancer relation, study says

Adults who experienced physical abuse as children seem to be more likely to go on to develop cancer, according to University of Toronto researchers. News Staff

One theory suggests that ongoing stress in childhood permanently damages the immune system.

The study, to be published July 15 in the journal Cancer, found that childhood physical abuse is associated with a stunning 49 per cent increased risk of cancer in adulthood.

Many childhood abuse survivors face a lifetime of problems and sometimes substance abuse. But this study took into account major health factors, such as smoking, alcohol consumption and lack of physical activity, and still found a strong link between abuse and cancer.

The study used data from the 2005 Canadian Community Health Survey, focusing on the provinces of Manitoba and Saskatchewan. Of the 13,092 respondents, 7.4 per cent reported they had been physically abused as a child by someone close to them, and 5.7 per cent reported that they had been diagnosed with cancer by a health professional.

Childhood physical abuse was associated with 49 per cent higher odds of cancer. The odds ratio decreased only slightly to 47 per cent higher odds when the numbers were adjusted to account for unhealthy adult behaviors, socioeconomic status, and other stressors during childhood, such as divorce.

Principal researcher Esme Fuller-Thomson of U of T's Factor-Inwentash Faculty of Social Work and Department of Family and Community Medicine says she was rather shocked by her own findings.

"I was totally surprised that that relationship was so strong," she told CTV News. "So there is something going on, but right now it is a black box. It is a question mark right now."

Fuller-Thomson says there are many possible reasons why physical abuse might increase the risk of cancer, though they are just theories.

One is that perpetual stress that an abused child experiences raises levels of the "fight or flight" hormone, cortisol. Elevated levels of the hormone might inhibit the immune system's ability to detect and destroy cancer cells.

"With every stressor, you respond with a huge amount of this hormone which sends your heart beat up and can cause suppression of your immune system," Fuller-Thomson explained. "And so that is one potential hypothesis."

Diana Ermel, president of the Canadian Breast Cancer Network worries that the study will add to the stress that many childhood cancer survivors carry with them.

"People who are often already suffering from the effects of childhood abuse have yet another fearful kind of thing put in front of them. it just adds to any sort of suffering that they might have and it is an unnecessary fear," she says.

Ermel notes that even if the data are right and childhood abuse survivors do have a higher risk of cancer, the absolute risk of any one person developing cancer is still small.

"It's just going to add to the burden of possible long-term side effects that they're already suffering with that they may think, 'Oh gee, now i'm going to get cancer.""

Fuller-Thomson stresses the findings need to be replicated in other larger studies before anyone could say that abuse is a risk factor for cancer. She says more research is needed to explain the higher cancer rates her study found and to better understand what mechanisms might be involved.

"Most people who are physically abused are actually healthy and cope well, but some people may be more vulnerable," says Fuller-Thomson.

"It warrants further research."

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