LOS ANGELES -- Could stress play a role in the development of breast cancer? Researchers from the University of Illinois at Chicago wondered about this. After all, the components of what experts call "psychosocial stress" -- including fear, anxiety and isolation -- could take a toll on the autonomic nervous system, which helps regulate heart rate, respiration and other important bodily functions.
So they found 989 women who had been diagnosed with breast cancer in the previous three months and asked them a lot of questions to assess their level of stress. It turned out that there was an association between stress and the disease -- the women who scored highest for stress were more likely to have a more aggressive form of breast cancer.
More specifically, the researchers found that stressed women were 38 percent more likely to have cancers that were estrogen receptor-negative. These tumors do not respond to therapies aimed at cutting off estrogen, which means that drugs like Tamoxifen, raloxifene (Evista), Arimidex and others will not help. After taking into account things like the women's age and the stage of their cancer when it was diagnosed, the women who were more stressed were still 22 percent more likely to have cancers that were estrogen receptor-negative.
The researchers also found that women with the most stress were 18 percent more likely to be diagnosed with high-grade tumors, which are more aggressive than low-grade tumors. However, when the study team accounted for age and cancer stage, the link disappeared.
In addition, breast cancer patients who were black or Latina had higher stress scores (on average) than patients who were white.
Of course, these results beg the question of whether the women with more aggressive cancers were already more stressed out before they were told they had breast cancer. It's certainly plausible that getting a breast cancer diagnosis -- especially if the tumor is aggressive -- would make a previously calm woman feel more than a bit agitated.
In a presentation made Monday at the American Association for Cancer Research's conference about health disparities and cancer, the research team acknowledged this problem. But for the sake of the study, they felt it was safe to assume that patients who were stressed when they were interviewed would also have been more stressed before they knew they were sick.
"It's not clear what's driving this association," lead researcher Garth Rauscher said in a statement. "It may be that the level of stress in these patients' lives influenced tumor aggressiveness. It may be that being diagnosed with a more aggressive tumor, with a more worrisome diagnosis and more stressful treatments, influenced reports of stress. It may be that both of these are playing a role in the association. We don't know the answer to that question."