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Report on the Relative Efficacy of Oral Cancer Therapy for Medicare Beneficiaries Versus Currently Covered Therapy

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Part 1. Gefitinib and Erlotinib for Non-Small Cell Lung Cancer


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 cancers shrink or disappear after treatment. RR = CR + PR. Because CR is uncommon in NSCLC, the overall response rate is the more common measure in studies of this disease.

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:

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

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 *: 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.

Except as noted, these definitions were quoted from the NCI's Web site.
* Definition derived from

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