201P Metastatic and survival characteristics of de novo versus relapsed breast cancer in females aged>35-years-old: A nationwide multicenter study based on hospital population

Abstract

It is uncertain how the metastatic and survival characteristics for de novo metastatic breast cancer (dnMBC) patients compare with relapsed metastatic breast cancer (rMBC) patients in the cohort aged>35-years-old. All subjects diagnosed with metastatic breast cancer were enrolled from 21 hospitals in 7 geographical regions of China during 2012-2014. The rMBC patients were divided into 4 groups based on metastasis-free interval (<12-month, 12∼36-month, 36∼60-month and >60-month). Overall survival (OS) and post-distant relapsed survival (PDRS) were compared using Kaplan-Meier curves. Multivariable COX regression was applied to analyze the adjusted hazard ratios (aHRs) for OS and PDRS with different metastatic situations. A total of 3075 subjects aged >35-years-old were included in this analysis. The proportion of dnMBC group and four rMBC groups were 17.3% (531), 9.9% (303), 36.2% (1114), 17.5% (538) and 19.2% (589), respectively. The dnMBC patients had a worse OS than rMBC individuals who relapsed later than 12 months (all P<0.001). The <12-month-rMBC and 12∼36-month-rMBC showed a worse PDRS than dnMBC (both P<0.001). For 12∼36-month-rMBC individuals, bone (HR 0.49, 95%CI: 0.29-0.78) or liver (HR 0.58, 95% CI: 0.42-0.80) metastases might be a protective factor for OS compared with dnMBC, but not for <12-month-rMBC group. Groups with <12-month-rMBC and 12∼36-month-rMBC did not show a significantly worse PDRS than dnMBC patients as for non-visceral metastases (HR<12m 1.25, 95%CI: 0.45-3.47; HR12∼36m 1.82, 95% CI: 0.94-3.54). This research showed that de novo breast cancer patients had a better PDRS than those who relapsed within 36 months, but had a worse OS than patients relapsed later than 36 months.