Cryoablation destroys tumours through freezing. Under ultrasound guidance a set of probes is inserted into the prostate, after which liquid argon is circulated through the probes. This freezes surrounding tissue to around −40 °C, thereby destroying the cells. The method has several advantages over surgery and radiation therapy, including a rapid recovery time and better success rates for moderate to high-risk cancers.

Unfortunately, freezing the entire prostate also damages nerves that are critical to potency. "Traditional thinking held that prostate cancer was multifocal and therefore not amenable to a focal treatment approach," said Gary Onik, a radiologist from Florida's Celebration Health Hospital (Celebration, FL), at the Radiological Society of North America (RSNA) annual meeting in Chicago, IL, in November last year. He has been pioneering focal cryoablation – a process via which only the cancerous area of the prostate is destroyed.

It is now known that around a quarter of prostate cancers are solitary and unilateral. This knowledge, together with recent imaging advances that allow radiologists to determine the extent of the cancerous tissue much more accurately, has made it possible to use cryoablation to freeze just the tumour – a technique that has become known as the male lumpectomy. Results obtained during the past few months show that, in the majority of patients, this focused therapy successfully preserves potency without compromising cancer control.

"When men are diagnosed with prostate cancer, often they have to decide between doing nothing and hoping that the cancer does not grow quickly, or choosing one of several treatments, all of which can have debilitating side-effects," said Onik. "Our preliminary research suggests that focused cryosurgery is an effective treatment and could provide a middle-ground choice for some men, as lumpectomy has been for the thousands of women who have chosen it over more invasive treatment options."

At RSNA, Onik presented results from 55 patients with an average follow-up time of 3.6 years. Of these, 52 showed no evidence of the cancer returning and potency was maintained in 86%. These results are backed up by another study, published in September, by a team from the Prostate Institute of America (Ventura, CA). In this case the researchers treated 21 men with focal cryoablation and found that 92.8% remained disease-free after a mean follow-up time of 70 months (J. Endourology 20 668).

"Today we are much more vigilant in diagnosing prostate cancer and as a result we are identifying the disease earlier and in younger men," said Duke Bahn, the study's lead investigator. "The outcomes we are seeing from focal cryoablation demonstrate that many of these patients now have a new option that not only is minimally invasive but also destroys the cancer, maintains their potency and quality of life, and can even be performed as an outpatient procedure in many cases," he added.

Focal cryoablation is not for every man. It can only be used on patients with cancers that are solitary and unilateral, or who have microscopic tumours smaller than 5 mm across. These types make up more than half of all cases, however, and this proportion could increase as screening techniques improve.

"The fact that cancer can be diagnosed much earlier than ever before and that many patients are looking for less-invasive treatments, with potentially fewer side-effects and complications, gives us continued confidence that the prospects for the increasing adoption of this therapy are very bright," said Craig Davenport, CEO of Endocare, the California-based company that manufactures the focal cryoablation equipment used in the studies.