A new study finds a link between aggressive breast cancer and stress. But the lead researcher suggests the findings raise as many questions as they answer.

The study included about 1,000 breast cancer patients in Chicago - white, black and Latina.

Soon after diagnosis, the women were interviewed to assess their level of stress. The researchers, led by Garth H. Rauscher of the University of Illinois at Chicago, compared the stress scores with the race of the patient and the aggressiveness of their cancers.

"Black and Hispanic patients reported greater levels of stress than whites did". "And we also found that patients reporting greater stress were more likely to have more aggressivetumors."

Previous research had found that American black and Latina women have, at the time they are diagnosed, more aggressive cancers than white women. But researchers can't decide if that's because minority women are somehow more susceptible to aggressive tumors, or because, for socioeconomic reasons, their cancers are more likely not diagnosed until the disease has advanced to a more aggressive stage.

So, is having the aggressive disease causing the stress, or is stress causing the disease? Maybe some third factor is involved.

Rauscher admits he's still a long way from the answer. "And so it's a very complicated issue to tease out what this means, other than to say that it suggests the possibility that there may be a biologic role of stress in the development of breast tumors that warrants further research."

The researchers were only able to do the stress interview after women were diagnosed with breast cancer, so they had to assume that the level of stress faced by the patients was the same before their diagnosis than after. But Rauscher concedes that is a limitation of his study.

"Therefore it's possible - even likely - that the process of diagnosis and the process of being treated influenced what they told us about their level of stress."

Raucher says more research is needed to better understand the relationship between stress and breast cancer. For a lot of reasons, it's probably good to minimize stress in our lives. But he cautions that his research does not mean that people who have had a stressful experience are necessarily at greater risk of aggressive breast cancer.

tumor: an abnormal new mass of tissue that serves no purpose 腫瘤

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（來源：VOA 編輯：張若瓊）