Telerobotic system designed to treat bladder cancer

The working end of the bladder cancer telerobot is only 5.5 millimeters in diameter and is shown in a glass flask about the size of a human bladder. (Joe Howell / Vanderbilt)

The specialized telerobotic system “doesn’t take the judgment out of surgeons’ hands, it enhances their capabilities and hopefully gives them surgical superpowers”

Although bladder cancer is the sixth most common form of cancer in the U.S. and the most expensive to treat, the basic method that doctors use to treat it hasn’t changed much in more than 70 years.

An interdisciplinary collaboration of engineers and doctors at Vanderbilt and Columbia Universities intends to change that situation dramatically. Headed by Nabil Simaan, associate professor of mechanical engineering at Vanderbilt, the team has developed a prototype telerobotic platform designed to be inserted through natural orifices – in this case the urethra – that can provide surgeons with a much better view of bladder tumors so they can diagnose them more accurately. It is also designed to make it easier to remove tumors from the lining of the bladder regardless of their location – an operation called transurethral recession.

“When I observed my first transurethral resection, I was amazed at how crude the instruments are and how much pushing and stretching of the patient’s body is required,” Simaan said.

That experience inspired the engineer to develop a system that uses micro-robotics to perform this difficult type of surgery. Its features and capabilities are described in an article titled “Design and Evaluation of a Minimally Invasive Telerobotic Platform for Transurethral Surveillance and Intervention” published in the April issue of the journal IEEE Transactions on Biomedical Engineering.

The specialized telerobotic system “doesn’t take the judgment out of surgeons’ hands, it enhances their capabilities and hopefully gives them surgical superpowers,” commented S. Duke Herrell, an associate professor of urologic surgery and biomedical engineering, who specializes in minimally invasive oncology at Vanderbilt University Medical Center and is collaborating on the project.

The traditional method, which Simaan observed, involves inserting a rigid tube called a resectoscope through the urethra and into the bladder. The instrument contains several channels that allow the circulation of fluid, provide access for an endoscope for observation and interchangeable cauterizing tools used to obtain biopsy tissue for evaluating the malignancy of the tumor and to resect small tumors. In some operations, surgeons replace the cauterizing tool with an optical-fiber laser to destroy tumor cells.

Although the endoscope can give a good view of the bladder lining directly across from the opening of the urethra, inspecting the other areas is more difficult. The medical team must press and twist the scope or push on the patient’s body to bring other areas into view. These contortions are also necessary when removing tumors in less accessible areas.

If the surgeon, using endoscopic observation or biopsy, determines that a tumor is invasive and has penetrated the muscle layer, then he later performs a cystectomy that removes the entire bladder through an incision in the abdomen. Frequently this is done using a normal surgical robot. But, when the surgeon judges that the tumor is superficial—restricted to the bladder lining—then he attempts to remove it using the resectoscope.

Bladder cancer is so expensive to treat in part because the tumors in the bladder lining are exceptionally persistent and so require continuing surveillance and repeated surgeries. Among the factors that contribute to this persistence is the difficulty of accurately identifying tumor margins and failure to remove all the cancerous cells.

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