One of the problems of first-line radiation therapy is how to treat patients with a rising PSA (biochemical relapse) after it becomes clear that the rise in PSA is not simply a “biochemical bounce” in the PSA.

Salvage radical prostatectomy is a feasible procedure, but it has long been recognized as a difficult operation, requiring great surgical skill, and with a high risk for significant complications. As a consequence, many patients with a rising PSA after first-line radiation therapy have historically had only hormone therapy as a serious second-line option for treatment.

Recently, improvements in cryotherapy have led to the increased use of this technique as a real second-line option for the salvage of patients in biochemical relapse following first-line radiation therapy. It is also possible to use high-intensity focused ultrasound (HIFU) as a similar salvage option (although access to HIFU in North America is limited at this time).

Earlier this year, Levy et al. published data providing some guidance about how well salvage cryotherapy patients can be expected to do over 3 years, based on their initial PSA levels after second-line treatment. This guidance is based on data from 455 hormone-naïve patients in the Cryo On Line Data Registry, all of whom were treated with whole-gland salvage croablation (SCA) of the prostate and were followed over time for PSA-based biochemical progression-free survival (bPFS) using the Phoenix criteria.

Levy and his colleagues categorized patients into three groups:

• Group A had an initial PSA level of < 0.6 ng/ml after SCA and included 280 patients.
• Group B had an initial PSA level between 0.6 and 5 ng/ml after SCA, and included 118 patients.
• Group C had an initial PSA level of > 5 ng/ml after SCA, and included 57 patients.

Follow-up of these patients over time showed that:

• For patients in Group A
  • 80 percent were biochemical progression-free at 12 months.
  • 73.6 percent were biochemical progression-free at 24 months.
  • 67 percent were biochemical progression-free at 36 months.
• For patients in Group B
  • 28 percent demonstrated biochemical progression at 6 months.
  • 50 percent demonstrated biochemical progression at 12 months.
• For patients in Group C
  • 64 percent demonstrated biochemical progression at 6 months.

The authors conclude that curative therapy remains extremely challenging for patients who show clear signs of relapse after first-line radiotherapy, and that there is no clear definition of clinical success after cryotherapy when used in the salvage setting. However, an initial PSA level of <0.6 ng/ml after SCA does suggest a promising 3-year outcome in about two-thirds of patients with such an initial response. By contrast, more than half the patients with initial PSA levels of ≥ 0.6 ng/ml after SCA are at risk of short-term biochemical progression within 1 year.

It is the ultimate big chill: cryotherapy, a minimally invasive procedure that involves exposing cancer cells or other diseased tissue to extreme cold. Some researchers are saying that this approach may be an effective cancer treatment option for patients whose cancer has spread (metastasized) beyond its original site in soft tissues and in bone tumors, since these individuals often are not candidates for surgery.

Cryotherapy, which is also known as cold therapy, cryosurgery, or cryoablation, involves introducing liquid nitrogen or argon gas to diseased sites inside or outside the body. The procedure is commonly used to treat skin lesions, such as skin tumors and skin tags, and it is also a treatment option for people who have cancer of the prostate, liver, cervix, and other tissue. When used internally, physicians utilize imaging techniques such as ultrasound or computed tomography (CT) to guide them to the treatment sites.

At the Society of Interventional Radiology’s 35th Annual Scientific Meeting in Tampa, researchers presented the results of a study in which cryotherapy was used to treat 97 patients who had cancer that has metastasized in soft tissues and in bone tumors. A total of 157 cryotherapy procedures were performed using computed tomography and/or ultrasound for guidance. The average tumor size was 3.5 centimeters, and the average treatment diameter was 5.4 centimeters. After two years, the tumors had shrunk an average of 77 percent.

Cryotherapy has been used for some time to treat prostate and liver cancers, but recently it has also proved successful in breast, lung, and kidney tumors. In this study, the authors took the procedure one step further. “We simply translated this concept to retroperitoneal, intraperitoneal [both refer to the abdominal cavity area], superficial and bone locations in order to generate successful use of cryotherapy in different patients groups,” says Peter J. Littrup, MD, an interventional radiologist and director of imaging research and image-guided therapy for the Barbara Ann Karmanos Cancer Institute in Detroit, Michigan.

In addition to its effectiveness in shrinking tumors, cryotherapy offers other benefits, including minimal pain, the ability to be performed in an outpatient setting, and quick healing with minimal scarring. The needle-like cryoprobes used to deliver the “big chill” have gotten smaller over the years, which now makes it possible to perform cryotherapy through a tiny incision in the skin.

Once the cryoprobes have reached their mark, extremely cold gas is delivered to the tumor. The freezing gas destroys the tumor cells, and surgeons also make sure their treatment reaches at least a 1-centimeter margin around the tumor to ward off further cancer spread. Littrup noted that because cryotherapy was successful in treating tumors in so many different sites, this demonstrates that it is versatile and that it can be performed while preserving underlying structures.

The authors projected that given the number of new cases of cancer diagnosed each year (1.5 million) and that up to 85 percent of breast, prostate, and lung cancer patients have bone metastases when they die, approximately 500,000 of newly diagnosed cancer patients will have their cancers spread to bone or soft tissue. Cryotherapy is an effective option for these individuals.

This latest study of cryotherapy showed that the procedure can “preserve quality of life by providing good local treatment with minimal side effects, especially with advanced stages of cancer where any additional treatment is unlikely to provide a systemic cure,” notes Littrup. Even though cryotherapy is effective for many cancer patients, health insurance may not cover the treatment.

SOURCE:
Society of Interventional Radiology