Sometimes size doesn't matter: reevaluating RECIST and tumor response rate endpoints.

If you give a cancer patient a drug and then the tumor’s growth screeches to a halt or a hole appears in its middle, most people would say the drug was working. But on the basis of the response criteria most widely used for solid tumors, these changes mean nothing. Standardized response criteria are critical for directing individual patient care, evaluating new therapies, and communicating risk to family and patients. Yet just what those criteria should be for solid tumors is up for debate. Although some groups are looking for new ways to physically measure success, others are moving away from tumor measurements altogether and strictly examining survival. “ I think standardizing response assessment is generally a good thing because people speak the same language when they are reporting studies, ” said Primo N. Lara, M.D., associate professor of medicine at the University of California at Davis in Sacramento, who presented on the topic at the American Society of Clinical Oncology annual meeting. “ Some people misinterpret a tumor response as being an end-all or be-all for a particular study, but our study showed that even if you don’t have a [measurable] response, having stable disease or nonprogression at a certain time point is a good predictor of outcome. You may not need to have a nice 30% reduction in tumor size to benefi t from a treatment. ”