Complete response (CR)

The disappearance of all signs of cancer in response to treatment. This does not always mean the cancer has been cured.

Partial response (PR)

A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment.

Response rate (RR)

The percentage of patients whose cancer shrinks or disappears after treatment. RR = CR + PR

Stable disease (SD)

Cancer that is neither decreasing nor increasing in extent or severity.

Progressive disease (PD)

Cancer that is growing, spreading, or getting worse.

RECIST criteria

RECIST criteria are a voluntary, international standard for measuring tumor response based on measurable disease (i.e., the presence of at least one measurable lesion). RECIST criteria offer a simplified, conservative, extraction of imaging data and presume that linear measures are an adequate substitute for 2-D methods. There are four response categories:

1. CR = disappearance of all target lesions.
2. PR = 30% decrease in the sum of the longest diameter of target lesions.
3. PD = 20% increase in the sum of the longest diameter of target lesions.
4. SD = small changes that do not meet above criteria.

SWOG criteria^b

SWOG criteria are based entirely on CT or MRI:

• CR = disappearance of all disease that could be measured and evaluated.
• PR = ≥ 50 percent decrease in the sum of the products of the perpendicular diameters of all measurable lesions, the absence of progression, and the absence of new lesions.
• PD = ≥ 50 percent increase or an increase of 10 cm² (whichever was smaller) in the sum of the products of the perpendicular diameters of all measurable lesions, worsening of a lesion that could be evaluated, the reappearance of and lesion or the presence of a new lesion.
• SD = a response that did not qualify as a complete response, a partial response or disease progression.

Overall survival

The percentage of subjects in a study who have survived for a defined period of time. Usually reported as time since diagnosis or treatment. Also called the survival rate.

Time to progression

A measure of time after a disease is diagnosed (or treated) until the disease starts to get worse.

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.

Disease-free survival

Length of time after treatment during which no cancer is found. Can be reported for an individual patient or for a study population.

Event-free survival^c

Length of time after treatment that a participant in a clinical study remains free of pre-defined events. Events are defined by the study and can include adverse treatment effects, tumor recurrence/progression, or survival.

Survival rate

The percentage of people in a study or treatment group who are alive for a given period of time after diagnosis. This is commonly expressed as 5-year survival.