ORLANDO, Fla.—Brachytherapy offers superior five-year overall and cancer-specific survival compared with external beam radiotherapy (EBRT) in the treatment of localized prostate cancer (PCa) with high recurrence risk features, researchers reported at the annual Genitourinary Cancers Symposium

The investigators noted that their findings are contrary to current treatment guidelines for treating localized PCa.

Anteneh Tesfaye, MD, a third-year internal medicine resident at McLaren Flint Medical Center in Flint, Mich., and colleagues analyzed data from 73,867 patients with localized PCa (T1-2 N0M0) who underwent radiation treatment. A total of 24,661 patients (33.4%) had brachytherapy and 49,206 (66.6%) had EBRT. The researchers stratified patients into three categories depending on their risk for recurrence: low risk (T1, T2a and PSA level below 10 ng/mL, and a Gleason score of 6 or less); intermediate risk (T2b or PSA of 10-20 ng/mL, or Gleason score of 7); and high risk (T2c or PSA above 20 ng/mL, or Gleason score of 8 or higher).

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The five-year overall survival rates were 95% for the brachytherapy and 92% for the EBRT patients in the low-risk group, 94% and 88%, respectively, in the intermediate-risk group, and 87% and 82%, respectively, in the high-risk group. All of these differences between the treatment groups were statistically significant.

The five-year cancer-specific survival rates were 100% and 99% for the brachytherapy and EBRT groups, respectively, in the low-risk group, 99% and 98% in the intermediate-risk group, and 97% and 94% in the high-risk group. The difference in rates between the brachytherapy and EBRT groups were significant among patients had low and high risk of recurrence, but not for those at intermediate risk.

In multivariate analysis, EBRT was associated with a significant 47% increased mortality risk.

The researchers noted that their study did not look at adverse events associated with these radiotherapies.

The data for the study were obtained from the Surveillance Epidemiology & End Results (SEER) database.