In order for a new treatment modality to be considered efficacious, it needs to be evaluated by acceptable criteria and demonstrate an improvement on the natural course of the disease. This has not been the case for focal therapy for prostate cancer.
Indeed, focal therapies for prostate cancer (see Table on page 29) are associated with considerable morbidities and have not been proven to cure prostate cancer, or at least reduce the morbidity of this disease, according to Michael O. Koch, MD, chairman of the department of urology at Indiana University in Indianapolis.
No so fast, countered Mark Emberton, MD, senior lecturer in oncologic urology at University College London. In Dr. Emberton’s estimation, focal therapy offers a definite alternative to radical prostatectomy for men who want active surveillance.
Dr. Koch and Dr. Emberton scrutinized the role of prostate focal therapy during a debate at the 2009 Genitourinary Cancers Symposium in Orlando.
No potential to cure prostate cancer
Studies of focal therapy suffer from lack of long-term data. “The longest published follow up with thermal ablative approaches to prostate cancer treatment is four years,” said Dr. Koch, who is also the John P. Donohue Professor of Urology at Indiana university. “At four years, the expected prostate cancer mortality would be approximately 4%. This number is too small for any of the published series to have adequate power and follow up to prove or disprove efficacy.”
While it may be premature to outright dismiss focal therapy, it is possible to say that the modalities are associated with morbidity, including rectal fistulas, urethral sloughing, impotence, and incontinence. “Focal therapies are not sham surgery in the sense that they do not treat the prostate,” he said. “They are sham surgeries, however, in the sense that they do not consistently ablate the entire prostate.”
He added that the available trials with focal therapy have been poorly controlled, have used inappropriate endpoints, and did not offer conclusive evidence of efficacy.
A two-year follow-up study by a group in Florida found that 94% of their patients (45 of 48) who were treated with focal cryoablation had stable PSA scores based on ASTRO criteria. All biopsy results were negative in the 24 patients with stable PSA scores who routinely had biopsies, and no local recurrences were noted in treated areas. In 36 of 40 patients who were potent preoperatively, potency was maintained to the satisfaction of the patient. All 48 patients in the study were continent (Urol Oncol 26:500-505, 2008).
“Since these modalities do have toxicity, they should be considered sham techniques until their potential to cure prostate cancer, or at least reduce the morbidity of the disease, can be demonstrated,” he said.
In order to believe that focal therapy is appropriate, it is necessary to believe that the cancer can be accurately staged within the prostate and that all of the significant tumors can be detected. In addition, one has to believe that focal therapy can consistently and effectively treat all the tumor foci. And finally, “you have to believe that treatment of the detected tumor foci will improve the morbidity or the mortality resulting from this disease and it should be better than what you can do with just surveillance,” he said.