In light of a general decline in breast cancer death since the late 1980s, research has now turned to how type and stage of disease affect survival among different women. These findings, which considered tumor size and estrogen-receptor (ER) status, were reported in the Journal of Clinical Oncology.
The death rate from breast cancer overall has been declining in much of the Western world during the past few decades. More recently, researchers have looked at improved survival rates for specific types of breast cancers and which patients are benefiting. Specifically, a recent study looked at survival by tumor size and ER) status according to cancer stage and patient age.
Researchers collected information on breast cancer-specific death from the National Cancer Institute’s Surveillance, Epidemiology, and End Results 9 Registries Database. The data had been collected from 1973 to 2010. Their goal was to estimate the risk of death from breast cancer from the time of diagnosis with invasive disease and how factors including tumor size and ER status influenced survival among different age groups and stages of disease.
They found improvements in survival for women younger than 70 with both local disease at diagnosis and cancer spread to more distant sights. Overall, the rate of cancer-specific death for patients diagnosed with breast cancer had declined from 1973 to 2010. This decline occurred within the first five years diagnosis and later.
When the researchers looked at survival according to tumor size, they found that size was associated with only 17% of the improvements when they compared survival from 1973 to 1979 with rates from 2005 to 2010. Smaller tumor size appeared to have the most impact on survival within five years after diagnosis and for patients 70 years old and older.
When the researchers evaluated survival according to ER status—including positive, negative, and unknown—they didn’t find that ER status had much influence on survival in general. One set of patients, however, did appear to have less risk of death within five years of diagnosis if their tumors had an unknown ER status: women 70 years of age and older.
Because tumor size and ER-status didn’t appear to significantly influence breast cancer survival in women younger than 70, it’s likely that treatment is the main reason behind declining death rates. For women age 70 and older, however, smaller tumor size and unknown ER status appeared to be linked to better survival within five years of diagnosis.
Reference: 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 [early online publication]. July 20, 2015.
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