It can yield good outcomes in some men with intermediate-risk prostate cancer.
Patients with intermediate-risk prostate cancer may be effectively treated with brachytherapy without supplemental pelvic radiotherapy, according to new findings.
The role of brachytherapy in treating intermediate-risk prostate cancer has been controversial. It risks undertreating extracapsular and seminal vesicle disease extension, although studies have shown that such most extracapsular extension is within 5 mm of the prostate capsule and could be treated appropriately with high-quality brachytherapy without supplemental pelvic radiotherapy.
Javier F. Torres-Roca, MD, of the H. Lee Moffitt Cancer Center at the University of South Florida in Tampa, and his colleagues examined outcomes of 88 patients with intermediate-risk prostate cancer who were treated with brachytherapy without supplemental pelvic radiotherapy; patients were followed for a minimum of 36 months (median, 57 months).
The researchers defined intermediate-risk prostate cancer as tumors with a Gleason score of 7 and/or PSA level between 10 and 20 ng/mL, and/or clinical stage greater than T2a but less than T3a.
All patients were treated with an iodine-125 transperineal seed implant with a total dose of 160 Gy delivered to the prostate, and 55 patients received pre-brachytherapy short-term androgen blockade. Biochemical failure was defined according to the American Society for Therapeutic Radiology and Oncology criteria.
Overall five-year biochemical failure-free survival was 83%, the investigators reported in Urologic Oncology (2006;24:384-390). The five-year biochemical failure-free survival was significantly decreased in patients with perineural invasion (64% vs. 89%).
The use of short-term androgen blockade did not significantly influence the biochemical outcome at five years (90% with no hormonal therapy vs. 85% with hormonal therapy). Markers of low-volume disease (i.e., number of positive cores, percentage of core involved with cancer) were not associated with biochemical failure.
Outcomes were not significantly influenced by Gleason scores 6 vs. 7, primary Gleason grades 3 vs. 4, clinical stage T1 vs. T2, number of positive cores, pretreatment PSA level less than 10 ng/mL vs. 10 ng/mL or greater, or one intermediate risk factor vs. two or more intermediate risk factors.
“The most suitable patients for brachytherapy monotherapy are pro-bably those with T1c disease and either Gleason 7 and PSA less than 10 or Gleason 6 and PSA between 10 and 20 with small volume disease,” Dr. Torres-Roca told Renal & Urology News.
“Before proceeding with brachytherapy monotherapy we would probably recommend an MRI of the prostate with an endorectal coil to rule out any extracapsular or extraprostatic extension.”