UNDERSTANDING BREAST CANCER SURVIVAL RATES
Chances for survival vary by stage of breast cancer.
Non-invasive (stage 0) and early stage invasive breast cancers (stages I and II) have a better prognosis than later stage cancers (stages III and IV). And, cancer that has not spread beyond the breast has a better prognosis than cancer that has spread to the lymph nodes.The poorest prognosis is for metastatic breast cancer (stage IV), where the cancer has spread beyond the lymph nodes to other parts of the body.
Overall survival rates
An overall survival rate shows the percentage of people who are alive after a certain period of time after diagnosis of a disease (such as breast cancer).For example, say the five-year overall survival for women with stage I breast cancer was 90 percent. This would mean that 90 percent of women diagnosed with stage I breast cancer survive at least five years after diagnosis. And, most of these women would live much longer than five years past their diagnoses.
Overall survival varies by breast cancer stage. People diagnosed with stage 0, I or II breast cancers tend to have higher overall survival rates than people diagnosed with stage III or IV breast cancers.However, overall survival rates are averages and vary depending on each person’s diagnosis and treatment.
Relative survival rates
Relative survival compares survival rates for women with breast cancer to survival rates for women in the general population.For example, say the five-year relative survival for stage II breast cancer was 85 percent. This would mean that women with stage II breast cancer were, on average, 85 percent as likely as women in the general population to live five years beyond their diagnosis.
Say, the five-year relative survival for women with stage I breast cancer was 100 percent. This would mean that women with stage I breast cancer were, on average, just as likely as women in the general population to live five more years.
As with overall survival, relative survival rates are averages and vary depending on each person’s diagnosis and treatment.
Population survival rates
Summary cancer staging is the most basic way to stage any type of cancer, including breast cancer. It is used to assess survival at the population level.
Summary cancer staging is also called SEER staging because it is used by the Surveillance, Epidemiology, and End Results (SEER) program, a part of the National Cancer Institute. SEER collects cancer data in the U.S. and compiles national cancer statistics.
SEER breast cancer survival rates are vital to researchers, advocates and policymakers. However, they are less helpful in estimating survival for individuals because the stages are defined so broadly.
Figure 4.8 below shows five-year relative breast cancer survival rates based on SEER staging.
For example, the five-year relative survival for localized breast cancer is 99 percent. This means women with localized breast cancer are, on average, 99 percent as likely as women in the general population to live five years beyond their diagnoses. These rates are averages and vary depending on a person’s diagnosis and treatment.
Because the categories of summary/SEER staging are defined so broadly, these statistics are more helpful to researchers, advocates and policymakers than to individuals.