Bracytherapy provides solid biochemical outcomes across all risk groups

September 1, 2005

Chicago--For early-stage prostate cancer, "brachytherapy has emerged as the weapon of choice," said Gregory Merrick, MD, of the Schiffler Cancer Center and Wheeling Jesuit University in West Virginia, in his opening remarks at the Windy City Shoot-Out here.

Citing the increased use of prostate brachytherapy over the past 15 years, Dr. Merrick emphasized well-documented, favorable biochemical control rates achieved with brachytherapy for all risk groups.

"Cryotherapy has no long-term data, unlike brachytherapy," said Dr. Merrick in his rebuttal to James Lugg, MD, who presented data on the advantages of cryotherapy over brachytherapy in early prostate cancer treatment. "Prior to being accepted as a mainstream treatment, cryotherapy must prove it can obtain durable biochemical control."

Not just for low-risk patients

Although a misconception that brachytherapy is effective only among low-risk patients remains, Dr. Merrick emphasized that brachytherapy is efficacious in patients with a high risk of extracapsular extension, but a low risk of pelvic lymph node involvement. Radical prostatectomy series have demonstrated that extracapsular extension is limited to 5 mm or less in 99% of patients. With his technique, which uses extracapsular seeds, Dr. Merrick's group has demonstrated that extracapsular treatment margins of 6 mm are routinely obtained following brachytherapy.

Going against the argument that brachytherapy is not appropriate in high-risk, hormone-naive patients, Dr. Merrick quoted multiple studies from five research groups demonstrating the efficacy of brachytherapy in this setting, especially when combined with supplemental external beam irradiation to the pelvic lymph nodes. He even suggested that the biggest advantage of brachytherapy compared with competing local modalities may be in high-risk patients.

Higher risk at higher dose?

James Lugg, MD, assistant clinical professor at the University of Colorado in Denver, questioned the true benefit of brachytherapy in high-risk patients, citing results that show higher rates of morbidity associated with higher radiation doses, with the most severe morbidity sometimes occurring late in the course of treatment. Moreover, he cited the high acute urinary retention rates following brachytherapy among patients with high pretreatment International Prostate Symptom scores, noting that one series showed 37% acute urinary retention after brachytherapy. He also cited the high rates of dysuria, which, he added, is typically recalcitrant to treatment and is often significantly debilitating.

Arguing for the benefit of cryotherapy in this setting, Dr. Lugg highlighted the low rates of urinary retention and rarely seen cases of dysuria following cryotherapy, along with its favorable biochemical disease-free survival rates.

Dr. Merrick acknowledged that 2% to 32% of patients develop acute urinary retention after brachytherapy, but noted that the duration of catheter dependency is short.

In his series, 88% of patients have the urinary catheter removed on the day of implantation and only 1% remain catheter dependent for more than 1 week. In addition, with appropriate medical management, including the use of prophylactic alpha-blockers, IPSS resolves significantly faster than in patients not receiving such therapy, Dr. Merrick pointed out.

In prospective randomized trials, IPSS scores returned to baseline at 4 months following brachytherapy. In terms of potency, brachytherapy is comparable with other modalities, with about 39% of men retaining potency, said Dr. Merrick, who added that phosphodiesterase type-5 inhibitors have been very helpful in managing erectile dysfunction.

Additionally, Dr. Merrick argued against the bias to use nonsurgical approaches in younger patients, citing a 10-year, 96% rate of biochemical control (PSA <.4 ng/mL after nadir) with a mean follow-up of 5.5 years in men <55 years of age.

Dr. Lugg questioned how 96% of patients can have PSA <.4 ng/mL at 5 years, when 20% to 40% of patients will experience a PSA bump after brachytherapy.