Good old cold therapy still useful, future bright

Dallas - Although competing modalities have stolen some of cryotherapy's thunder, technical advances under development could one day restore cryotherapy's luster, an expert says.

"Cryosurgery remains the mainstay of therapy for many skin lesions, particularly tumors, in spite of the fact that so many other physical therapeutic modalities have been introduced in dermatology during the last few years," says William Abramovits, M.D., professor of dermatology, Baylor University Medical Center, Dallas.

Such modalities include heat from electrodesiccation, lasers or intense pulsed light (IPL) devices, he says.

"Over the last few years," he adds, "A paucity of technological developments (in cryotherapy) has allowed other treatment modalities to gain some terrain against cryosurgery."

But in the not-too-distant future, instrumentation that's being added to the cryosurgery unit will bring cryosurgery back to the attention of many dermatologists, Dr. Abramovits predicts.

More specifically, he says he's used prototypes featuring temperature gauges that utilize laser interferometry to allow measurement of target temperature without piercing the skin.

"These will facilitate the interpretation of how long and how deep the temperature at the target has been sustained," Dr. Abramovits explains.

While cryosurgery remains widely used for lesions such as warts and actinic keratoses, he says, "Cryosurgery has lost the most ground in the treatment of malignancy," due partly to the wide availability of Mohs surgery.

Cold therapy techniques offer a level of certainty that all malignant cells have been removed that cryosurgery does not provide, Dr. Abramovits adds.

"However," he tells Dermatology Times, "I prognosticate that in the near future the use of ultrasound and confocal microscopy will allow the cryosurgeon to match the cryodestructive front to the lesion's margin."

Measuring up to Mohs

With modernized equipment, Dr. Abramovits explains, "We will be able to detect where the –10 degrees to –50 degrees Celsius cryodestructive front or isotherm (area of uniform temperature) is located," ensuring that the zone of destruction reaches the last cancerous cell without destroying surrounding tissue.

In that sense, Dr. Abramovits says, "I'm hoping that within this decade, as the price of imaging equipment comes down, cryosurgery will do the work of Mohs much less invasively."

The technology is available, but presently too cumbersome for widespread use, he adds.

Currently, cryosurgery remains useful for treating benign, precancerous and cancerous lesions, he says. It works by lowering lesion temperature below a critical level for a period of time sufficient to cause destruction, explains Dr. Abramovits, who estimates he uses this modality at least 20 times daily.

A typical treatment involves spraying the lesion, plus 1 mm to 3 mm of visible margin, with liquid nitrogen or another freezing agent for 30 to 60 seconds, he says.

Because of cryotherapy's speed and ease of use, he adds, "A dermatologist can treat multiple lesions at one visit at a relatively low cost to the patient or payor."

Effectiveness operator-dependent

However, Dr. Abramovits cautions that cryosurgery's effectiveness is operator-sensitive.

"In the hands of a skilled operator," he contends, "cryosurgery almost always provides excellent outcomes." But cryosurgery performed by unskilled operators can create morbidities including unduly large blistering or nerve compromise, he says.

"Although cryosurgery looks easy," Dr. Abramovits says, "it isn't easy to do it well."

Therefore, he says he prefers that cryosurgery never be delegated to physician extenders.