The role of progesterone receptor (PR) status on the association between obesity and prognosis of estrogen receptor positive (ER+) breast cancer (BC) remains poorly understood.
However, the obesity factor impacted more in the ERα<sup>+</sup>/PR<sup>+</sup> group since the ratio between OB and non-obese (NOB) patients with high expression of HIF1-α and SLUG was higher in ERα<sup>+</sup>/PR<sup>+</sup> than in the ERα<sup>-</sup>/PR<sup>-</sup> group. miR-221 levels were significantly higher in the OB than NOB patients, and, also in this case, obesity impacted more in the ERα<sup>+</sup>/PR<sup>+</sup> group.
Although it has been well-documented that obesity is associated with decreased risk of premenopausal breast cancer and increased risk of postmenopausal breast cancer, it is unclear whether these associations differ among breast cancer subtypes defined by the tumor protein expression status of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2).
Adding dichotomous tumor ER or PR status to the panel of standard predictors did not improve both model discrimination and calibration.<b>Conclusions:</b> Obesity may be associated with greater endometrial tumor expression of ER and PR.
Obesity and overfeeding affecting both tumor and systemic metabolism activates the progesterone receptor to contribute to postmenopausal breast cancer.