Older patients with small kidney tumors are up to 70% less likely to die from any cause when managed by watchful waiting rather than by surgery, based on findings from a large retrospective study.
Surveillance appears to be safe for these small lesions, with a kidney cancer mortality of just 3% over a 5-year period. In addition, watchful waiting seems to confer a cardiovascular benefit; these patients had a 49% lower cardiac mortality risk compared with that for patients who had kidney surgery, said lead author Dr. William C. Huang of New York University Medical Center.
The link between kidney surgery and heart problems is probably mediated by compromised kidney function, Dr. Huang said. "It’s believed that when surgery takes excess normal kidney tissue, it hastens the acceleration of kidney failure," leading to cardiovascular problems, he said.
The study findings are going to be increasingly valuable as imaging turns up more and more incidental asymptomatic kidney tumors. Last year alone, about 65,000 of these lesions were diagnosed, most of them during a work-up for other abdominal complaints.
While the trend toward surveillance of small asymptomatic lesions is growing, Dr. Huang said surgery is still the treatment mode for more than half of cases. Most procedures in the retrospective study were radical nephrectomies, with kidney removal in about half of those. "The majority of these small lesions could be removed laparoscopically, but even then you’re taking out normal kidney tissue that you might really want back someday," he said at a press briefing at the Genitourinary Cancers Symposium, sponsored by the American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Urologic Oncology.
"Physicians can comfortably tell an elderly patient, especially a patient who is not healthy enough to tolerate general anesthesia and surgery, that the likelihood of dying of kidney cancer is low and that kidney surgery is unlikely to extend their lives," he said. "However, since it is difficult to identify which tumors will become lethal, elderly patients who are completely healthy and have an extended life expectancy, may opt for surgery."
The study examined mortality data in the Surveillance, Epidemiology, and End Results database for 8,317 patients, aged 66 years or older, who were diagnosed from 2002 to 2007 with kidney tumors smaller than 1.5 cm. The patients were followed for a median of 59 months; 78% were managed with surgery and 22%, with surveillance. The use of surveillance increased over the course of the study, from about 25% in 2002 to almost 40% in 2007.
Over the study period, 2,078 (25%) of the patients died, including 277 (3%) who died of kidney cancer. At least one cardiovascular event occurred in 24% of the patients.
Kidney cancer mortality rates did not vary between the treatment groups. However, surgical patients had a significantly increased risk of death from any cause. At 7-36 months, those who had surveillance were 30% less likely to have died than those managed by surgery (hazard ratio, 0.70). After 36 months, patients were 63% less likely to have died if their tumors were managed by surveillance instead of surgery (HR, 0.37).
Dr. Huang also demonstrated that those in the surveillance group experienced a significant cardiovascular benefit as well. By the end of the study, 25% of the deaths were due to a cardiovascular event. Patients in the surveillance group had a 49% reduction in the chance of an event.
Dr. Huang said he had no relevant financial disclosures.