Abstract: Background and purpose: Metastasis remains the cause of 90% of death from cancer. By analyzing the distribution of metastatic sites and survival status of 20 000 metastatic cancer patients from a hospital-based cancer registry database, this study provides the real-world data for the cancer treatment and survival management in China. Methods: A total of 20 067 cancer patients who were diagnosed as having metastatic caner or developed metastasis during the follow-up in Fudan University Shanghai Cancer Center from 2008 to 2017 were included in this study. Medical records review, telephone visits and death registry data linkage were applied in collecting endpoint data. The first follow-up date was the diagnosis date of metastasis, and the last follow-up date was November 1, 2020. Kaplan-Meier method was applied in evaluating the 1-, 3- and 5-year overall survival (OS) rates for overall cancer and site-specific cancer patients. Results: The median follow-up time was 46.7 months, 13 170 cases died during the follow- up, 60.05% was single-site metastasis, and 39.95% was multiple-site metastasis. Among all metastable sites, the proportion of metastasis to liver was 33.82%, 26.25% to lung, 26.22% to bone, and 9.22% to brain. The incidence of brain metastasis was the highest in lung cancer patients among all cancer types (31.14%). Liver was the most frequent metastatic site in pancreatic cancer (77.85%), and bone was the most frequent metastatic site in patients with prostate cancer (83.20%). Subgroup analysis showed that liver metastasis was easier to be observed in males than in females (35.46% vs 31.89%, P<0.001), whereas lung, bone and brain metastases were more frequently to be observed in females (24.96% vs 27.76%, 25.26% vs 27.34%, 8.34% vs 10.25, P<0.001). After metastasis, the 1-, 3- and 5-year OS rates of overall cancer were 65.59% (95% CI: 64.90-66.27), 33.42% (95% CI: 32.69-34.16) and 21.12% (95% CI: 20.39-21.84), respectively. Conclusion: The metastasis patterns for different cancer sites are different, and there is sex heterogeneity. Currently, the survival rate after metastasis is poor, and the future research combining with treatment strategies is required to improve the survival of advanced-stage cancer patients.

Key words: Cancer, Metastasis, Survival rate, Hospital-based registry