Profile and outcome of receptor conversion in breast cancer metastases: a nation‐wide multicenter epidemiological study

Abstract Although receptor status including estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) of the primary breast tumors was related to the prognosis of breast cancer patients, little information is yet available on whether patient management and survival are impacted by receptor conversion in breast cancer metastases. Using data from the nation‐wide multicenter clinical epidemiology study of advanced breast cancer in China (NCT03047889), we report the situation of retesting ER, PR and HER2 status for breast cancer metastases and evaluate the patient management and prognostic value of receptor conversion. In total, 3295 patients were analyzed and 1583 (48.0%) patients retesting receptor status for metastasis. Discordance in one or more receptors between the primary and the metastatic biopsy was found in 37.7% of women. Patients who remained hormone receptor (HR) positive in their metastases had similar progression‐free survival of first‐line and second‐line treatment compared to patients with HR conversion ( P > .05). In multivariate analysis, patients who showed ER conversion from negative to positive had longer disease‐free survival (DFS) than patients who remained negative in their metastases (hazard ratio, 2.05; 95% confidence interval [CI], 1.45‐2.90; P < .001). Patients with PR remained positive and had longer DFS than patients with PR conversion from negative to positive (hazard ratio, 0.56; 95% CI, 0.38‐0.83; P = .004). Patients with PR conversion have shorter overall survival than patients with PR remained positive or negative ( P = .016 and P = .041, respectively). Our findings showed that the receptors' conversions were common in metastatic breast cancer, and the conversion impacted the survival.