What is Chemosensitivity?

Chemosensitivity is a measurement of a tumor's level of susceptibility to chemotherapy drugs. When tumors are very sensitive, the cancer will respond better to treatment, as the medications can kill the tumor and prevent the growth of new cells. More resistant tumors may be difficult to treat and can require a mixture of drugs, radiation, and other options to successfully control the cancer. When a doctor diagnoses a patient with cancer, the patient may meet with an oncologist to discuss therapies, and this meeting can include a recommendation for chemosensitivity testing.

In the testing, samples of cells from the cancer are sent to a lab. A technician grows them in culture and tests them with various popular chemotherapy drugs. Lab personnel can also look for receptors on the cancer to check for sensitivity to specific medications. Breast cancers, for example, are often sensitive to particular drugs because of the presence of estrogen receptors on the surface of the cells. The lab can generate a report to provide information to the oncologist supervising the patient's case.

In chemotherapy, the doctor wants to keep the regimen as gentle as possible to spare healthy cells and reduce side effects. Chemosensitivity testing can help a doctor design a custom drug therapy for the patient's cancer. Drugs known to be ineffective are not part of the therapy, and the doctor can adjust and tweak the dosage of useful drugs to hit the sweet spot where the patient gets enough medication to treat the cancer, but not so much that he experiences side effects as a result of toxicity.

For some cancers, chemosensitivity testing is not necessary, as they tend to perform in predictable ways. The testing can be expensive and the doctor may prefer to start the patient on therapy right away, without waiting for test results. In other cases, this testing can be a very important part of developing an appropriate treatment plan; the doctor does not want to start chemotherapy without a list of potentially effective drugs.

During cancer therapy, the doctor will ask for medical imaging studies and other diagnostic tests to follow the progress of the treatment. It may be necessary to adjust medications and dosages, and to consider alternate modes of therapy if the patient's cancer does not respond well to treatment. Doctors also have to consider toxicity and side effects. A medication may work very well as a result of high chemosensitivity, but if the patient cannot tolerate it, it may be necessary to explore a different drug.