A new study has reported that the risk of locoregional recurrence (in the breast, chest wall, or lymph nodes) is higher among very early stage breast cancer patients with mixed estrogen receptor (ER) and progesterone receptor (PR) status than it is among those with ER+/PR+ disease. Generally speaking, patients with tumors that are positive for either ER or PR are considered hormone receptor positive for purposes of making treatment decisions. However, some reports have suggested that patients with mixed hormone receptor (ER+/PR- or ER-/PR+) tumors may have worse outcomes than those with ER+/PR+ disease. Little data is available concerning how having mixed hormone receptor tumors may influence the risk of locoregional recurrence.
To conduct the study, the authors examined medical records of 635 patients with very early stage (small, lymph node negative) disease who were treated between 1997 and 2002. Tissue that had been saved from the participants were used to verify ER/PR expression. Outcomes of the 479 patients who had ER+/PR+ tumors were compared to the outcomes of the 156 patients with ER+/PR- or ER-/PR+ tumors.
Locoregional recurrence rates were found to be substantially higher in patients with mixed hormone receptors compared to those with ER+/PR+ disease (8.8% compared to 2.5% over the first seven years after diagnosis). However, having only one positive receptor was not associated with higher locoregional recurrence in patients who received hormonal therapy such as an aromatase inhibitor. No differences were found between the two groups in the rates of distant metastasis or overall survival, perhaps reflecting the favorable overall prognosis of this very early disease stage. The authors conclude that patients with small, node-negative breast cancer with only one positive hormone receptor have increased rates of locoregional recurrence compared with patients with ER+/PR+ disease, although this difference may be reduced or eliminated with systemic treatment.