Abstract
Improvement in breast cancer survival has been observed in recent decades in the U.S., but it is unclear if similar survival gains are consistent across breast cancer subtypes, especially with regards to more advanced stages of the disease. Data were from 13 population-based cancer registries participating in the surveillance, epidemiology, and end results (SEER) program, consisting of women between 20 and 79 years of age diagnosed with invasive breast cancer between 1992 and 2008. 2-year (1992-2008) and 5-year (1992-2006) breast cancer cause-specific survival rates were calculated and stratified by estrogen receptor (ER)/progesterone receptor (PR) status, stage, and race. Annual percent changes in survival rates were assessed. From 1992 through 1998-1999, 5- and 2-year cause-specific survival rates significantly improved across ER+/PR+, ER-/PR-, and ER+/PR- subtypes, with an annual increase ranging from 0.5 to 1.0 % in the 5-year rates. From 1998-1999 to 2006, different patterns were observed by ER/PR subtypes with survival rates slightly improving for ER+/PR+, continuing to improve at a rate of 0.5 % per year for ER-/PR-, and dropping 0.3 % annually for ER+/PR-. No significant survival gains were experienced by patients with ER-/PR+ cancer during the study period. In terms of advanced diseases, greatest annual increases in survival rates were seen for patients with stage III-IV ER+/PR+ and ER-/PR- tumors but less progress was observed for advanced ER+/PR- breast cancers. Steady improvements in survival rates for breast cancer have been achieved over the past several decades. However, 5-year survival rates for stage IV disease remained dismally below 20 % for most ER/PR subtypes.