In order to understand survival data, it is important to understand what survival rates are. The survival rate for a particular disease refers to the percentage of patients with that disease who are alive at a given point in time following their diagnosis.
Survival rates for cancer are typically:
- Measured at yearly intervals over a period of five years, starting on the day a patient was first diagnosed.
- Organized by cancer type as well as stage of disease at diagnosis. Stage refers to how advanced a cancer is – for example, stage I is less advanced than stage III, and the data for each will be presented separately because they have different expected survival rates.
Our survival rates are presented in the form of line graphs. Each graph includes a set of curved lines: one red line and one blue line.
Memorial Sloan Kettering survival rates
The blue curve represents the percentage of Memorial Sloan Kettering patients who are alive at each yearly interval following diagnosis and treatment.
Only those patients who were originally diagnosed at Memorial Sloan Kettering, or received all or part of their first course of treatment from Memorial Sloan Kettering, are included in the data. The vast majority of these patients (more than 90 percent) were originally diagnosed at Memorial Sloan Kettering or elsewhere and received part or all of their first course of treatment from Memorial Sloan Kettering physicians. The rest are patients who were diagnosed at Memorial Sloan Kettering but received treatment elsewhere.
This approach allows us to evaluate the outcomes of our care – and can help you compare the results of care we provide to that of other treatment centers.
National Cancer Data Base survival rates
The red curve represents the percentage reported by the National Cancer Data Base (NCDB), a collaborative effort of the American College of Surgeons and the American Cancer Society.
The survival rates reported by the NCDB reflect data provided by more than 1,500 accredited cancer programs across the United States and Puerto Rico, including Memorial Sloan Kettering. The methods used to collect and report this information are well established, rigorous, and consistent across participating institutions, and routinely audited. Data from the NCDB is generally considered to be both reliable and of high quality.
We present our data alongside that of the NCDB so you can compare our patients’ rate of survival with that of the national average. In general, you will see that our survival rates are better than the national average.
Reading the graphs
Example: Survival Rates for Women with Stage I Breast Cancer
The example you see at right shows survival rates for women with stage I breast cancer. The numbers listed on the left-hand side of the graph indicate the percent of patients with stage I breast cancer who are alive at a given point in time. The numbers across the bottom of the chart indicate the number of years that have passed since initial diagnosis.
The blue line indicates survival among Memorial Sloan Kettering patients diagnosed with stage I breast cancer in 2003. Reading the chart from left to right shows you the percentage of stage I breast cancer patients who are living at one, two, three, four, and five years after diagnosis: 99.4 percent in 2004, 99.4 in 2005, 98.8 in 2006, 97.8 in 2007, and 96.5 in 2008. The red line indicates survival for the same years as reported by the NCDB: 99.0 percent in 2004, 97.7 in 2005, 96.0 in 2006, 94.0 in 2007, and 91.8 in 2008.
You will note that our data is based on patients who were first diagnosed ten years ago. The same is true of the NCDB data and of all data provided by cancer programs participating in the NCDB. This is because patient outcomes are tracked over five years; it then takes additional time to complete data collection and ensure its accuracy. As a result, survival rates do not take into account the impact of the most recent advances in treatment.
Additional information on how to read survival curves is included on the graphs themselves.