How big is the kidney tumor? If it's small, less than 4 centimeters, "upwards of 30 percent are benign, not even cancer," says Phillip Pierorazio, M.D. "Of the 70 percent left, half are low-grade, indolent tumors that are not ever going to cause a problem. That only leaves about a third that are potentially aggressive." This is good news: many of these people can safely avoid surgery.

Who can safely avoid surgery? Although several institutions have studied surveillance, these studies have mainly been retrospective, after-the-fact. "Few institutions have followed their patients to make sure that active surveillance is a safe option for them," says Pierorazio. Six years ago, he and urologist Mohamad Allaf, M.D., the Mohamad E. Allaf Director in Minimally Invasive Urology and Buerger Family Scholar, set out to change this. They started the Delayed Intervention and Surveillance for Small Renal Masses (DISSRM, pronounced "disarm") Registry for patients with small kidney tumors, and their groundbreaking work is paving the way for people with small kidney cancers to be treated worldwide. Since 2009, they have followed more than 200 patients; Pierorazio and Allaf recently published their results in European Urology.

"Our DISSRM Registry follows not only patients on active surveillance, but those who have undergone surgery, as well," says Pierorazio. In general, he says, the people who undergo active surveillance are older, sicker and have smaller tumors. "However, these patients have done incredibly well. No patient undergoing active surveillance has had kidney cancer spread from the kidney, and none has died of kidney cancer. These early results demonstrate that active surveillance is a safe option for patients with small kidney tumors and, at least, not inferior to surgery in the short term." About 10 percent of those who undergo active surveillance end up having surgery, "either because of changes in the tumor or their health status, making surgery a more attractive option." The next step for the Registry, he says, is to continue to refine selection criteria for active surveillance, to learn more about the significance of growth rates, and to measure quality of life for people in the program.