positive at the time of diagnosis, since they are then useful in detecting a recurrence of metastatic cancer and for monitoring therapy.
Monitoring Response to Treatment For either recurrent or metastatic disease, appropriate studies are done to determine response to treatment. Before any significant change in therapy—a new chemotherapy program, for example—it is essential to establish baseline information, documenting current status by blood tests, examinations, measurements and x-rays.
Objective clinical response is ordinarily defined as at least a 50 percent shrinkage in the greatest diameter of a metastatic lesion .
A metastatic tumor in the lung 11/2 in. (4 cm) in diameter would have to shrink to 3/4 in. (2 cm) for this to be called a significant response, with such shrinkage being classified as a partial response. A complete response or remission occurs when all visible and detectable disease disappears.
"Stable disease" suggests disease that does not grow in any area or shrinks by less than 50 percent in diameter (also called minimal response).
Disease progression means that at least one lesion increases in size during treatment.
• It is easy to assess lung metastases. Measurements can be made with a ruler held against a chest x-ray.
• Lesions in the liver can be monitored by liver function tests , especially the alkaline phosphatase , but also by
direct measurement of metastatic tumors seen on abdominal CT or ultrasound images.
• Skin lesions and the size of lymph nodes can be measured directly.
