Freezing Kidney Cancers Shows Promise
FRIDAY March 13, 2009 -- Most kidney cancer tumors can be eradicated using a noninvasive freezing technique that eliminates the need for surgery, a pair of studies from Johns Hopkins Hospital suggests.
The findings have prompted the researchers to claim that the procedure, known as cryoablation, should be the new "gold standard" of treatment for kidney cancer -- although not all cancer experts agree.
"Here we found that we can very successfully treat kidney cancer tumors, and get rid of them completely, by essentially freezing them," said the lead author of one of the two studies, Dr. Christos Georgiades, an interventional radiologist at Hopkins.
"The only caveat," he cautioned, "is that the data we have concerns treating kidney cancers that are smaller than 5 centimeters -- about 2 inches -- in diameter. But I would say that for tumors that are up to 4 centimeters in diameter, cryoablation -- freezing -- should be the first option for treatment, not surgery."
Georgiades and his colleagues presented the findings Monday at the Society of Interventional Radiology annual meeting in San Diego.
Cryoablation uses high-tech imaging to locate tumors, along with small probes inserted through a tiny hole in the skin to direct freezing cold to the trouble spot. It is usually performed as a one-day outpatient treatment and is already widely available in hospitals throughout the United States.
However, the Hopkins team pointed out that current protocols place solid emphasis on surgical removal (laparoscopy) as the standard approach to kidney cancer, with cryoablation relegated to a fallback role for high-risk patients who are battling multiple illnesses, limited kidney function or multiple or recurring tumors or who have problems undergoing anesthesia.
The study authors noted that kidney cancer strikes 54,000 Americans -- mostly older adults -- every year and ultimately takes the lives of 13,000 people a year.
Although the risk for developing the cancer is about one in 75, Georgiades and his team point out that 75 percent of kidney cancer diagnoses are made while the tumor is still relatively small and potentially most responsive to cryoablation.
For their study, the researchers tracked the success of cryoablation in tackling 73 renal-mass tumors, 10 of them benign, in 68 people who averaged 67 years old. CT or MRI imaging was done three, six and 12 months after the procedure to assess tumor status. Participants were followed for two to three years.
They found that cryoablation destroyed localized tumors up to 4 centimeters in diameter 100 percent of the time. Tumors up to 7 centimeters in size (about 3 inches) were destroyed "nearly" 100 percent of the time, and in the few cases in which tumor size was large -- about 10 centimeters, or roughly 4 inches, in diameter -- cryoablation was successful two-thirds of the time, the study found.
There was no evidence of any cancerous spread to areas outside the kidney during follow-up, the authors noted.
In the second Hopkins study, researchers spent up to two years tracking complications after cryoablation among 73 people who had 81 procedures. No treatment-related deaths occurred, and though there were complications in just over 7 percent of the cases, the team concluded that the technique has an "excellent safety profile."
Despite the findings, Georgiades said, problems with tumor location mean that there will always be people who need surgery.
"The great success we had with cryoablation assumes that not only is the tumor small enough but also that we can successfully get to it from the outside with probes," he explained. "So tumors that are too deep or too close to vital organs might not be targetable," he said, noting that no such patients were included in the study. "This type of patient will need surgery. But this problem would affect only maybe one-quarter to one-third of patients. For the rest, cryoablation should be the first option."
Georgiades said that freezing is already the "first-line treatment" for small kidney cancer tumors at Hopkins.
However, Dr. Paul Russo, an attending urologic oncological surgeon at Memorial Sloan-Kettering Cancer Center in New York City, argued strongly against the notion that cryoablation now be considered the "gold standard" for kidney cancer treatment.
"To suggest that freezing should be the new 'gold standard' is … very naive because the treatment of small renal masses is a highly complex area in kidney tumor management, and ablation is largely an investigative technique that simply has not yet been studied well."
"For example, one of the ways in which this particular study is flawed is that, after ablation, they conducted much too short a follow-up to perform any kind of meaningful survival analysis," Russo noted. "Almost nothing happens in the first year. To assess the effectiveness of any kidney cancer treatment you really need active surveillance for at least a five-year period, which they didn't do."
"The study's conclusions are a huge overstatement," he added. "Freezing is just one treatment option. Nothing more."
The American Cancer Society has more on kidney cancer.
Posted: March 2009