De novo and recurrent metastatic breast cancer - A systematic review of population-level changes in survival since 1995.

ABSTRACT

BACKGROUND: Advances in breast cancer (BC) care have reduced mortality, but their impact on survival once diagnosed with metastasis is less well described. This systematic review aimed to describe population-level survival since 1995 for de novo metastatic BC (dnMBC) and recurrent MBC (rMBC). METHODS: We searched MEDLINE 01/01/1995-12/04/2021 to identify population-based cohort studies of MBC reporting overall (OS) or BC-specific survival (BCSS) over time. We appraised risk-of-bias and summarised survival descriptively for MBC diagnoses in 5-year periods from 1995 until 2014; and for age, hormone receptor and HER2 subgroups. FINDINGS: We identified 20 eligible studies (14 dnMBC, 1 rMBC, 5 combined). Potential sources of bias in these studies were confounding and shorter follow-up for the latest diagnosis period.For dnMBC, 13 of 14 studies reported improved OS or BCSS since 1995. In 2005-2009, the median OS was 26 months (range 24-30), a median gain of 6 months since 1995-1999 (range 0-9, 4 studies). Median 5-year OS was 23% in 2005-2009, a median gain of 7% since 1995-1999 (range -2 to 14%, 4 studies). For women ≥70 years, the median and 5-year OS was unchanged (1 study) with no to modest difference in relative survival (range -1·9% (p = 0.71) to +2·1% (p = 0.045), 3 studies). For rMBC, one study reported no change in survival between 1998 and 2006 and 2007-2013 (median OS 23 months). For combined MBC, 76-89% had rMBC. Three of four studies observed no change in median OS after 2000. Of these, one study reported median OS improved for women ≤60 years (1995-1999 19·1; 2000-2004 22·3 months) but not >60 years (12·7, 11·6 months). INTERPRETATION: Population-level improvements in OS for dnMBC have not been consistently observed in rMBC cohorts nor older women. These findings have implications for counselling patients about prognosis, planning cancer services and trial stratification. FUNDING: SL was funded in part by a National Health and Medical Research Council (NHMRC) Project Grant ID 1125433. NH was funded by the NBCF Chair in Breast Cancer Prevention grant (EC-21-001) and a NHMRC Investigator (Leader) grant (194410). BD and SAP were funded in part by the NHMRC Centre of Research Excellence in Medicines Intelligence (1196900).