Clinical information and management status of de novo stage IV breast cancer patients: a Chinese multicenter investigation (CSBrS-002)

BACKGROUND: Although de novo stage IV breast cancer is so far incurable, it has entered an era of individualized treatment and chronic disease management. Based on systemic treatment, whether the surgical resection of primary or metastatic foci of de novo stage IV breast cancer can bring survival benefits is currently controversial. We aimed to explore the clinicopathological factors and current status of the management of de novo stage IV breast cancer in China to provide a reference for clinical decisions. METHODS: Based on the assistance of Chinese Society of Breast Surgery, a retrospective study was conducted to analyze the clinical data of patients with de novo stage IV breast cancer in 33 centers from January 2017 to December 2018. The relationship between basic characteristic (age, menstrual status, family history, reproductive history, pathological type, estrogen receptor [ER] status, progesterone receptor [PR] status, human epidermal growth factor receptor 2 [HER2] status, Ki-67 percentage, and molecular subtype), and metastasis sites (lung metastasis, liver metastasis, and bone metastasis) was examined by Pearson Chi-square tests. RESULTS: A total of 468 patients with de novo stage IV breast cancer were enrolled. The median age of the enrolled patients was 51.5 years. The most common pathological type of primary lesion was invasive carcinoma (97.1%). Luminal A, luminal B, HER2 overexpressing, and triple-negative subtypes accounted for 14.3%, 51.8%, 22.1%, and 11.8% of all cases, respectively. Age, PR status, and HER2 status were correlated with lung metastasis (χ(2) = 6.576, 4.117, and 8.643 and P = 0.037, 0.043, and 0.003, respectively). Pathological type, ER status, PR status, and molecular subtype were correlated with bone metastasis (χ(2) = 5.117, 37.511, 5.224, and 11.603 and P = 0.024, <0.001, 0.022, and 0.009, respectively). Age, PR status, HER2 status, Ki-67 percentage, and molecular subtype were correlated with liver metastasis (χ(2) = 11.153, 13.378, 10.692, 21.206, and 17.684 and P = 0.004, <0.001, 0.001, <0.001, and 0.001, respectively). Combined treatment with paclitaxel and anthracycline was the most common first-line chemotherapy regimen for patients with de novo stage IV breast cancer (51.7%). Overall, 91.5% of patients used paclitaxel-containing regimens. Moreover, 59.3% of hormone receptor-positive patients underwent endocrine therapy. CONCLUSIONS: In 2018, 1.07% of patients from all studied centers were diagnosed with de novo stage IV breast cancer. This study indicated that 95.1% of patients received systemic therapy and 54.2% of patients underwent surgical removal of the primary lesion in China.