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Kaplan-Meier survival curve
Short explanation
The Kaplan-Meier estimate is a simple way of computing the survival curve in spite of all these troublesome research subjects. It involves computing the number of people who died at a certain time point, divided by the number of people who were still in the study at that time. We multiply these probabilities by any earlier computed probabilities, which is one reason this is called a "product limit estimate."
The Kaplan-Meier survival curve is often illustrated graphically. It looks like a poorly designed staircase, with vertical steps downward at the time of death of each individual subject.
Often we will compare curves for two different groups of subjects. For example, what is the survival pattern for subjects on a standard therapy compared to a newer therapy. We can look for gaps in these curves in a horizontal or vertical direction. A vertical gap means that at a specific time point, one group had a greater fraction of subjects surviving. A horizontal gap means that it took longer for one group to experience a certain fraction of deaths.
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Second Example
medcalc.be
Why use it?
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Progression-free survival.
This term defines the length of time during and after treatment that the cancer does not grow. Progression-free survival includes the amount of time patients have experienced a complete response or a partial response, as well as the amount of time patients have experienced stable disease.
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progression-free survival
One type of measurement that can be used in a clinical study or trial to help determine whether a new treatment is effective. It refers to the probability that a patient will remain alive, without the disease getting worse.
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Progression-free survival rate.
This is the number of people who still have cancer, but their disease isn't progressing. This includes people who may have had some success with treatment, but their cancer hasn't disappeared completely.
Partial remission, or partial response.
A partial remission, or partial response, indicates there has been a decrease in tumor size, or in the extent of cancer in the body, after treatment. The definition of "partial" is different for every cancer. In most cases it means tumors must be reduced by more than 50 percent — and stay that way for at least six months after treatment. But in clinical trials, new guidelines define a partial response as a reduction in tumor size of at least 30 percent.
Stable disease.
A tumor may shrink, but not enough to be categorized as a partial response (that is, tumor reduction greater than 50 percent). Or a tumor may increase in size, but not enough to be considered progressive disease (that is, tumor growth greater than 20 percent). Such tumors, in which there is no significant change in size, are classified as stable disease.
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Disease-free survival rate.
This is the number of people with your cancer who achieve remission. That means they no longer have signs of cancer in their bodies.
partial response
A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment. Also called partial remission.
stable disease
Cancer that is neither decreasing nor increasing in extent or severity.
objective response
A measurable response.
response rate
The percentage of patients whose cancer shrinks or disappears after treatment.
palliative therapy (PAL-ee-yuh-tiv)
Treatment given to relieve the symptoms and reduce the suffering caused by cancer and other life-threatening diseases. Palliative cancer therapies are given together with other cancer treatments, from the time of diagnosis, through treatment, survivorship, recurrent or advanced disease, and at the end of life.
What is a cancer survival rate?
Cancer survival rates or survival statistics tell you the percentage of people who survive a certain type of cancer for a specific amount of time. Cancer statistics often use a five-year survival rate. For instance, the five-year survival rate for prostate cancer is 99 percent. That means that of all men diagnosed with prostate cancer, 99 of every 100 lived for five years after diagnosis. Conversely, one out of every 100 died of prostate cancer within five years.
Survival rates are based on research that comes from information gathered on hundreds or thousands of people with cancer. An overall survival rate includes people of all ages and health conditions diagnosed with your cancer, including those diagnosed very early and those diagnosed very late.
Your doctor may be able to give you more specific statistics based on your stage of cancer. For instance, 49 percent, or about half, of people diagnosed with early-stage lung cancer live for at least five years after diagnosis. The five-year survival rate for people diagnosed with lung cancer that has spread (metastasized) to other areas of the body is 3 percent.
Overall and relative survival rates don't specify whether cancer survivors are still undergoing treatment at five years or if they've achieved remission. Other types of survival rates that give more specific information include:
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