Impact of Prior Cancer History on the Clinical Outcomes in Advanced Breast Cancer: A Propensity Score–Adjusted, Population-Based Study

PURPOSE: Despite the rapid growing of cancer survivors, prior cancer history is a commonly adopted exclusion criterion. Whether prior cancer will impact the survival of patients with advanced breast cancer (ABC) remains uncertain. MATERIALS AND METHODS: Patients with ABC diagnosed between 2004 and 2010 were identified using Surveillance, Epidemiology, and End RESULTS: (SEER) database. Timing, stage, and type were used to characterize prior cancer. Multivariable analyses using propensity score–adjusted Cox regression and competing risk regression were conducted to evaluate the prognostic effect of prior cancer on overall survival (OS) and breast cancer-specific survival (BCSS). RESULTS: A total of 14,176 ABC patients were identified, of whom 10.5% carried a prior cancer history. The most common type of prior cancer was female genital cancer (32.4%); more than half (51.7%) were diagnosed at localized stage; most were diagnosed more than 5 years (42.9%) or less than 1 year (28.3%) prior to the index cancer. In multivariate analyses, patients with prior cancer presented a slightly worse OS (hazard ratio, 1.18; 95% confidence interval [CI], 1.07 to 1.30; p=0.001) but a better BCSS (subdistribution hazard ratio, 0.64; 95% CI, 0.56 to 0.74; p < 0.001). In subset analyses, no survival detriment was observed in patients with prior malignancy from head and neck or endocrine system, at in situ or localized stage, or diagnosed more than 4 years. CONCLUSION: Prior cancer provides an inferior OS but a superior BCSS for patients with ABC. It does not affect the survival adversely in some subgroups and these patients should not be excluded from clinical trials.