In monkeys, low social status doubled chances of disease

Social status may affect a woman's chances of developing endometrial cancer.

Although an absolute link has not been established, research done with monkeys points in that direction.

"Low social status is associated with markers of increased risk for endometrial cancer in postmenopausal primates," lead researcher Carol Shively, a professor of comparative medicine at Wake Forest University Baptist Medical Center , told HealthDay .

"It was a twofold increase," she continued. "This is not a little effect; it is a big effect." Results of the study were first published last year in the journal Menopause .

Endometrial cancer is cancer of the lining of the uterus. An estimated 1 percent to 2 percent of American women will develop endometrial cancer at some point in their life, according to the National Library of Medicine. It is most common in older women, peaking in women between 60 and 70 years old.

Factors that increase the risk of endometrial cancer include obesity, polycystic ovary syndrome, high blood pressure, never having been pregnant, diabetes, using estrogen-only hormone replacement therapy, a history of uterine polyps, and either early or late onset of menstruation.

Shively and her colleagues placed postmenopausal female monkeys into groups and allowed them to establish their own social hierarchy. Then they measured cell proliferation and sex steroid receptors in the lining of the uterus, as well as breast tissue thickness.

Past research had shown that subordinate monkeys were more likely to have faster heart rates, increased levels of stress hormones and a greater risk of cardiovascular disease than dominant monkeys.

"Low social status is stressful…in human beings and in monkeys," Shively said. "It appears that this stress carries with it health consequences"

The researchers found that the subordinate monkeys had double the risk of endometrial cancer that dominant monkeys had. They also exhibited thickening of breast tissue, which may indicate an increased risk for breast cancer as well, Shively said.

"But, this finding was not as compelling as the one for endometrial cancer," she added.

Shively said the findings are likely applicable to humans, in whom she said such a study would be impossible because of difference in access to health care due to socioeconomic status and racial differences.

"The reproductive system of these monkeys is similar to the human reproduction system, which makes them a good model for studying reproductive disorders and diseases," she said.

Kathleen Grant, co-author of an editorial that accompanied publication of the study, described the study's outcome as "a precautionary tale."

"Social stress, perhaps caused by increases in social isolation and hostile social experiences, or lack of control over social interactions, may place postmenopausal women at risk for breast and endometrial cancer," added Grant, who is a professor of physiology and pharmacology at Wake Forest University Baptist Medical Center .