Sophisticated new tools make cryotherapy, a prostate-cancer treatment, less invasive

By BILL KETTLER
Mail Tribune

Physicians have been freezing prostate tumors since the 1960s, but the results often left something to be desired.

Below-zero temperatures destroyed cancer cells as the prostate froze, but physicians lacked the ability to contain the cold within the walnut-sized gland. Men often came out of the procedure with damage to sensitive surrounding tissues — the urethra, the rectum and the urinary sphincter.

Side effects like those made patients and physicians alike wary of cryotherapy, but new technology has made it a much more sensitive tool. Physicians now use computers and ultrasound monitors to map the prostate and position the needles that freeze it. Sophisticated temperature monitors are placed in adjacent tissues and a warming catheter inserted in the urethra to minimize side effects.

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"The computer-generated map tells us where to insert the needles," says Dr. Eric Martin, a urologist who does "cryoablation" of the prostate at Providence Medford Medical Center. "We can fine-tune where all these things are going to go."

Martin says freezing the gland is a much less invasive procedure than removing it surgically. It’s also quick. A procedure usually takes about two hours, and men can typically go home the same day they enter the hospital.

"Most people don’t find it painful," Martin says.

Cryoablation involves little of the drama — or blood — most people associate with surgery. After a patient is anesthetized, an ultrasound monitor is inserted in the rectum. Sound waves are fed to a computer, which draws a map of the prostate on a screen. The computer determines where to insert two sets of needles. One group of six carries pressurized argon gas that freezes the gland; six more monitor the temperature of surrounding tissues.

A grid plate helps Martin insert each needle in the appropriate position, and ultrasound pictures of the gland let him check them for proper placement.

When everything is ready, the argon gas is fed into the freezing needles. The gas cools rapidly as it expands, creating a ball of frozen tissue around the end of each needle.

Martin monitors the size of each "iceball" by looking at images of the prostate produced by the ultrasound monitor. Saline solution pumped through the warming catheter prevents the urethra from freezing.

The gland is frozen to minus 40 degrees Celcius, thawed (by pumping helium gas through the freezing needles), refrozen and thawed once more. Martin says the two freezing cycles ensure that the gland and the cancer cells inside it are destroyed.

While freezing the prostate is less invasive than surgery, physicians usually limit it to men who are already impotent or are not interested in maintaining their potency. That’s because cryotherapy often destroys the blood vessels that are associated with erection.

Men who want to preserve their potency usually choose to treat their cancer surgically or with radiation, which have fewer erectile side effects.

Cryotherapy is also reserved mostly for cancer that is still localized within the gland and for men who whose prostate cancer returned after other treatments (such as radiation).

"It’s the gold standard treatment for men with recurrent cancer in the prostate," Martin says.

Patients like the procedure because it’s fast and relatively painless.

"I had a little tenderness in the bottom. That was about it," said Neil Watson of Medford, who underwent cryoablation in November.

Like most patients, Watson, 66, also had to wear a urinary catheter for about two weeks, but he says he was "back to normal within about two days after it was removed."

Martin says the procedure is a good example of "an old idea that’s been improved to make it safe and effective."

Reach reporter Bill Kettler at 776-4492, or e-mail bkettler@mailtribune.com.