Abstract P5-05-06: Menopausal status: An important consideration in determining the biology and prognosis of estrogen receptor-positive and progesterone receptor-negative breast cancer

Abstract

Abstract Background: Transcription of the progesterone receptor (PgR) gene is regulated by estrogen in the breast tissue. PgR loss is considered to be a result in the reduction of estrogen receptor (ER) activity, due to either low circulating estrogen in some older women or a high growth factor signaling. Among the ER-positive breast cancer patients, PR-negative cases frequently have a higher resistance to endocrine therapy, and have a poorer prognosis. Therefore, we examined the clinical significance of ER+/PgR- tumors in luminal/HER2 negative breast cancer and its relationship to menopausal status. Methods: The sample for this study came from 1791 consecutive patients with HER2 negative primary breast cancer from January 2002 to March 2013. The ER and PgR expressions were evaluated using immunohistochemistry (IHC). 1586cases had ER+/PgR+ tumor, 205cases had ER+/PgR- tumor. The items examined were nuclear grade, Ki-67 index value, TP53, tumor size and number of lymph node involvement. The Ki-67 index value and TP53 were evaluated using IHC and the cut-off values were 20% and 50%, respectively. Recurrence free survival (RFS) and breast cancer-specific survival (BCSS) was calculated using the Kaplan-Meier method and evaluated by the log-rank test or generalized Wicoxon test in stage 1 and 2 breast cancer. Results: In terms of the distribution of ER and PgR status, ER+/PgR- were frequently seen in postmenopausal patients (13.7% vs 6.8%, respectively). Patients with ER+/PgR-and HER2 negative tumors had significantly smaller tumors, lower Ki-67 values, and a lower nuclear grade in the postmenopausal group compared with those in the premenopausal group. Moreover, RFS trended to be better in the postmenopausal group (p = 0.06), but there was no significant difference. BCSS was significantly higher in the postmenopausal cases (p = 0.001). On the other hand, in patients with ER+/PgR+ tumors, there was no significant difference in RFS and BCSS between the post- and pre-menopausal groups. Conclusion: The ER+/PgR- tumors were more commonly seen in postmenopausal patients. The biological characteristics of ER+/PgR- tumors were significantly different in terms of the Ki-67 index value, nuclear grade, and the prognosis (BCSS and RFS) between pre- and postmenopausal status. Moreover, the postmenopausal group had a more favorable biology and prognosis than the premenopausal group. Therefore, the findings in this study indicate that menopausal status is related to the biology and prognosis in patients with ER+/PgR- tumors. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-05-06.