Medical Device Daily

ATLANTA – Kidney cancer is the third-leading “urologic-specific” cancer in the U.S., according to Christopher Kane, MD, of the University of California, San Francisco , and as such, it warranted special consideration at a press event during the American Urological Association 's (AUA; Linthicum, Maryland) annual meeting on Sunday.

Kane, who moderated the press conference, said that this area of urology is also among the most rapidly evolving, and the face of kidney cancer is “probably” changing more than any other urological cancer, he added. And his findings could potentially help – with further study – those who will be diagnosed with this form of cancer, which causes about 13,000 deaths each year.

Raj Pruthi, MD, of the University of North Carolina at Chapel Hill (Chapel Hill, North Carolina), said that the incidence of kidney cancer has increased about 3% per year for the past several years. Both the increase – and long-term damage from – smoking and the rise in obesity, two of the major risk factors, are thought perhaps to be the cause.

Kane said that more and more small tumors of the kidney are being detected today due to greater use of imaging, some of them less than 1 cm. The question becomes: should physicians treat immediately – typically with the gold standard of partial or whole organ removal – or do they wait?

“The majority of these tumors are picked up” through imaging, and are not found because the patient became symptomatic, Pruthi said.

The title of Pruthi's and his associates' study is “Expectant Management of Small Renal Masses: Does a Delay in Therapy Pose a Clinical or Pathological Risk to the Patient?”

In a study of 43 patients with 46 renal masses, the average tumor size in older patients (over age 70) for whom the decision was made to watch and wait was 3.1 cm.

Patients under 60 had “more rapidly growing tumors” than older patients, he said, with patients younger than 57 years.

Pruthi's abstract said that of the 46 masses, 15 subsequently underwent intervention at a mean interval of 13 months, including laparascopic partial nephrectomy (PN), open PN, laparoscopic radical nephrectomy and radio frequency ablation.

The average time from “observation” to treatment with intervention was 12 months.

At follow-up of 37 months, 13 of 14 patients were alive, with one patient dying due to other causes 30 months after surgery. No patient, according to the abstract, had “upstaging of disease secondary to delay.”

Pruthi's conclusion was that “watchful waiting for renal masses may be an appropriate option for the appropriately selected patients – especially those with competing morbidities.”

“There is no substitute for appropriate individual decision-making,” Pruthi advised, and acknowledged that the concept of watchful waiting is somewhat of a “gray area” in medicine, despite the fact that everyone wants the practice of medicine to be black and white.

Watchful waiting may also be made more difficult, Kane added, because “a lot of times when people are diagnosed” they want to have surgery, the current gold standard, within “weeks.”

Presenter Nicholas Hegarty, MD, the Endourology Research Fellow at the Glickman Urological Institute of the Cleveland Clinic Foundation (Cleveland) discussing a study on “Renal Cryoblation: 5 Year Outcomes,” agreed that “the approach to small, renal tumors is a very vexing problem.”

The approach to these types of tumors for urologists provides a “daily dilemma,” he said, noting that it's hard to determine “which are the pussycats and which are the tigers.”

Cryoablating involves placing one or more probes in the tumor to freeze it in order to destroy the cancerous tumor, which requires a temperature of -20⁰ Centigrade for “adequate cell kill,” Hegarty said.

The study involved 168 laparascopic cryoablations between September 1997 and September 2005 performed at the Cleveland Clinic. Of those, 60 patients have “now each completed at least five years follow-up since cryoablation.”

“Of these, the indication for treatment was a solitary sporadic renal lesion in 44 [73%],” the study said.

Three patients were known to have developed “local tumor recurrence, of which two have remained disease-free on dialysis following nephrectomy,” the study said. Another died 10 months after the nephrectomy on dialysis, but with no further evidence of disease.

There has been only one death from cancer.

Hegarty said the significance of the study is that it is the largest series that has been done with five-year follow-up.

Despite the encouraging outcome of the study of cryoablation, which he said is certainly more “convenient” than open surgery, Hegarty added, “Cryoablation is not without complications – it is still surgery.”

Another presenter, Noah Schenkman, MD, of Walter Reed Army Medical Center (Washington), said he and his colleagues performed a proof-of-concept study using the daVinci surgical system developed by Intuitive Surgical (Sunnyvale, California) for remote surgical applications for nephrectomy performed over the Internet.

He noted that while “remote telesurgery using monoscopic vision has been performed with the Zeus [developed by Computer Motion ] surgical robot, at a great financial cost [more than $1 million],” the daVinci has never previously been used due to what he termed its “complexity.”

Computer Motion was acquired by Intuitive in July 2003 (Medical Device Daily, July 2, 2003).

One of the advantages of the daVinci, according to Schenkman, is that it offers viewing in 3-D, which is “not normally available.”

The U.S. Army has always been interested in remote telesurgery, he said, due to the desire to be able to complete surgery on the battlefield from a remote location. The requirements of such a system, from the Army's perspective, are that it be “durable, wireless, low bandwidth and easily accessible to the surgeon in the field,” Schenkman said.

According to the study, the daVinci system was “modified to enable network communications between multiple [surgeons'] consoles and a single patient-side cart [the robot].” The system was evaluated in “dry lab” exercises via connections based in Cincinnati once and Denver a second time with resident surgeons in Sunnyvale, California. Combined, they performed surgeries on six pigs.

In the first attempt from Cincinnati, there was a 900-millisecond delay between the surgeon's moves and the movement on the end-system, which “made surgery very difficult” due to “poor visualization.” In a second attempt with Denver, the effort reduced delay to 450 milliseconds by increasing bandwidth to 8 megabytes, which was found to be “acceptable,” Schenkman said.

Schenkman concluded that such surgery is “doable,” and the study meant the accomplishment of several “firsts.”

“While a number of obstacles need to be overcome before telesurgery is widely accepted, the daVinci surgical system offers a unique opportunity to develop a network which may be used to extend the reach of expert surgeons,” the study said.