Within 5 years of breast cancer diagnosis, tumor size and estrogen-receptor (ER) status contribute greatly to survival improvement in women 70 years or older, according to a study published online ahead of print in the Journal of Clinical Oncology.
However, most stage-specific improvement in survival in those younger than 70 years is unexplained by tumor size and ER status.
“Breast cancer mortality began declining in many Western countries during the late 1980s,” said Ju-Hyun Park, PhD, of Dongguk University in South Korea as well as fellow study authors from the National Cancer Institute in Maryland. “We estimated the proportion of improvements in stage- and age-specific breast cancer survival in the U.S. explained by tumor size or ER status.”
The researchers estimated hazard ratios for breast cancer-specific death from time of diagnosis through Surveillance, Epidemiology, and End Results (SEER) data from 1973 to 2010, stratifying with and without tumor size and ER status.
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They found that breast cancer-specific death had declined within that time, even 5 years after the time of diagnosis. Tumor size was found to account for more of the survival improvement within the first 5 years of diagnosis than later.
In addition, survival improvement in those women who were at least 70 years was found to be explained more by tumor size and ER status, while stratifying for the same factors could not explain improvement in those younger than 70.
- Park JH, Anderson WF, Gail MH. Improvements in US breast cancer survival and proportion explained by tumor size and estrogen-receptor status. Journal of Clinical Oncology. 2015. [epub ahead of print]. doi: 10.1200/JCO.2014.59.9191.