Daijiworld Media Network - Cleveland

Cleveland, Oct 6: Low-dose-rate (LDR) brachytherapy guided by prostate-specific membrane antigen (PSMA) PET scans may offer an effective treatment for patients with locally recurrent prostate cancer, according to physicians at Cleveland Clinic.

Researchers analysed data from 105 patients whose recurrent prostate cancer was identified using PSMA-PET scans. The scans helped pinpoint the precise locations of the recurrences within the prostate, after which radioactive LDR brachytherapy seeds were implanted directly into the tumours.

The findings suggest that the targeted approach could be an effective alternative to higher-dose stereotactic body radiotherapy (SBRT), the researchers said. The results were presented on September 28 at the American Society for Radiation Oncology (ASTRO) meeting in Boston.

"To treat something that's essentially a tiny dot on the PET scan with SBRT would be overkill and fraught with side effects," said study lead Dr Jay Ciezki in a Cleveland Clinic release.

All 105 patients underwent focal salvage LDR brachytherapy following PSMA-PET identification of their recurrence. An iodine-125 dose of 144 Gy was prescribed, with a 0.5-cm treatment margin used except when the target was adjacent to the bladder, urethra or rectum. No margin was used in such cases to protect these structures.

Treatment effectiveness was assessed through prostate-specific antigen (PSA) readings and imaging, while treatment-related toxicity was also evaluated.

At a median follow-up of 22.3 months, 83 patients, or 79 per cent, had no evidence of disease, according to the study results. One patient died from the disease.

The researchers found that a longer interval before local failure and seminal vesicle treatment were significant factors associated with clinical failure following focal salvage LDR brachytherapy.

The treatment was also associated with relatively limited side effects. Ciezki described the side effects as "not zero, but darn close."

The researchers said further studies will examine whether the location of recurrence within the prostate influences treatment selection and outcomes. They also plan to investigate how PSMA-PET imaging can be better used to guide treatment decisions and improve outcomes.

"This is now an option for patients who have local recurrences that appears to be as good if not better than other treatment options," Ciezki said.