Circulating regulatory T cells in endometrial cancer: a role for age and menopausal status.

Regulatory T cells (Treg) are a sub-population of T cells that suppress self-reactivity and are implicated in immune tolerance towards malignant cells. Circulating Treg cells are increased in several cancers. In endometrial cancer Treg cells have been investigated only in tumour tissues and, in contrast to some other tumours, fewer Treg cells were reported in endometrial cancer compared with benign controls. Flow cytometry was used to determine the frequency of circulating Treg cells in women undergoing hysterectomy for either endometrial cancer (n = 24) or non- cancer-related conditions (n = 21). Circulating Treg cells were more abundant in women with cancer compared to those without (4.68% vs. 3.66%, p = 0.05, Mann-Whitney test). This relationship disappeared, however, when only data from post-menopausal women were included in the analysis. Mean Treg cell frequency was 4.65% in postmenopausal women with cancer (n = 23) and 4.73% in postmenopausal controls (n = 5) (p = 0.9). In women without cancer we found that mean Treg cell frequency was higher in postmenopausal women (4.73%, n = 5) in comparison to premenopausal controls (3.33%, n = 16) (p = 0.02). These results suggest that the increased proportion of Treg cells seen in endometrial cancer patients might be, at least in part, attributed to their postmenopausal status or age.