A new paper in BJU International offers an analysis of data on the effectiveness and safety of focal cryotherapy (partial cryoablation of the prostate) as a first-line treatment for localized prostate cancer from the national Cryo On-Line Database (COLD) registry collected between 1997 and 2007.
According to Ward and Jones, the registry includes data on a total of 5,853 patients treated through 2007. The following bullet points summarize the available information on the community use of focal cryotherapy collected in this registry:
- 1,160/5,853 procedures (19.8 percent) on patients listed in the database were coded as being focal forms of cryotherapy
- There was a major increase in the number of focal treatments between 1999 and 2005.
- 46 focal treatments were reported in 1999.
- 567 focal treatments were reported in 2005.
- The biochemical progression-free survival rate at 36 months was 75.7 percent (based on the ASTRO definition of biochemical recurrence).
- Post-treatment prostate biopsies were carried out on 164/1,160 patients (14.1 percent).
- Post-treatment biopsy was positive in 43 patients suspected of cancer recurrence (26.3 percent).
- Post-treatment biopsy was positive in only 43/1,160 of treated patients (3.7 percent).
- Urinary continence (defined as use of no pads at all) was 98.4 percent.
- Maintenance of spontaneous erections was reported in 58.1 percent.
- Prolonged urinary retention (> 30 days) occurred in 6/1,160 patients (1.1 percent).
- Rectourethral fistula was observed in 1/1,160 patients (0.1 percent).
It is evident from these data that focal cryoablation is becoming a more commonly accepted option for the treatment of carefully selected men with small, well-defined foci of prostate cancer.
What is not entirely clear from these data is whether the level of effectiveness of the therapy has increased over time with increasing accuracy of appropriate patient selection. The (median?) follow-up period in this review is brief at only 3 years, and only 14.1 percent of the patients were given a post-treatment biopsy, so long-term oncologic efficacy (at about 75 percent) needs to be evaluated with caution.
As the authors note, “impact of focal cryoablation on urinary, sexual and bowel function appears to be less than that of radical therapies.” The retention of sexual function among men with good erectile function prior to treatment, however, is relatively low. The loss of sexual function among a very high percentage of men undergoing whole gland cryotherapy has always been a problem. Whether better cryotherapeutic technique and better patient selection can help to address this issue in men undergoing focal cryotherapy still needs to be resolved.
Focal crotherapy is currently considered to be most appropriate as a treatment option for men with one or two small foci of prostate cancer in a single lobe of the prostate, clinical stage T1c or T2a disease, a PSA level of < 10 ng/ml, and a Gleason score no higher than 3 + 4 = 7. Most specialists offering this technique require their patients to undergo a second biopsy procedure,with not less than about 20 biopsy cores being taken, to maximize the probability that the cancer really is limited to a small area in one lobe of the prostate prior to focal treatment. Such biopsies may be conducted under color Doppler ultrasound or magnetic resonance imaging (MRI) for the greatest levels of accuracy.