92P The prognosis and predictive value of the negative estrogen/positive progesterone breast cancer profile (ER- / PR +): Moroccan experience

Abstract

The breast cancer endocrine therapy is importantly related to the expression of the steroid hormones, estrogen receptor (ER) and progesterone receptor (PR). They are one of the most efficace prognostics factors and predictive markers in the hormonal treatment. Progesterone receptors are often tested in parallel with estrogen receptor because extensive studies have shown that PR expression is conditional on ER activity. It is easier to decide treatment strategies in cases of double-positive/negative steroid hormones. On the other side, the existence of breast cancer with ER negative/PR positive phenotype is contentious. To describe the clinical features and outcomes of estrogen receptor negative (ER-) and progesterone receptor positive (PR+), we have retrospectively examined a large (1182 cases) and well-characterized database of primary breast cancer from 2012 to 2019. The cases were stratified according to ER and PR expression and we were focused on ER-/PR+ group to highlight their features and to figure any prognosis and predictive value in comparison with ER+/PR- and double positive/negative tumors. 1182 cases were explored, 112 patient (9%) had ER-/PR+, 749 (63,4%) had ER+/PR+, 92 (6%) had ER+/PR- and 229 (19,4%) were double negative. Compared with different groups of ER/PR expression all patients were younger at the time of diagnosis (median age 50 p=0,28 ). In comparison with ER+ the ER-/PR+ are most likely to be high grade (p<0,0001), in the other hand the ER-/PR+ groups are less likely to be high grade in comparison with double negative (p<0,0001). And more likely to have HER-2 over expressing/amplified tumors in comparison with the ER+ (p<0,0001). No significant difference was shown in tumor size (p=0,62), or with nodal metastases (p=0,17). As expected the majority of ER-/PR+ group received adjuvant endocrine therapy. In our series the ER-/PR+ breast cancer present 9% confirmed by the literature (2,3%-9%). This phenotype is associated with high grade and HER-2 over expressing/amplification, and appears more in younger women, presenting an aggressive behavior. The ER-/PR+ tumor is a clinically distinct group and it may need a different treatment strategies.