Definition of Partial Responder to Chemotherapy

Chemotherapy is a drug-based treatment designed to disrupt and kill malignant (cancerous) cells in the body. A partial responder to chemotherapy experiences a reduction in tumor size from treatment but does not experience complete tumor eradication.

Partial Response

• Doctors generally define a partial response to a given chemotherapy medication as a reduction in tumor size of greater than 50 percent that lasts for at least one month, according to the Medical College of Wisconsin.

Other Responses

• Other levels of response to chemotherapy include a full response, in which all detectable signs of a tumor disappear; disease progression, in which a tumor grows by more than 25 percent; and stable disease, which includes the range between partial response and progression, the Medical College of Wisconsin reports.

Alternate Definitions

• Doctors may also use other definitions of partial response when treating specific forms of cancer, according to Chemocare.

Varying Response Rates

• Response rates to different chemotherapy drugs vary according to the type of cancer under treatment, the stage of the cancer and whether drugs are used singly or in combination. Doctors derive this information by reviewing clinical studies and treatment protocols.

Treatment Planning

• Doctors commonly evaluate likely responses of a given type of cancer to chemotherapy when making their treatment plans, Chemocare notes.