High-dose-rate brachytherapy boost for prostate cancer: Outcomes and genitourinary toxicity

To report disease outcomes and late urinary toxicity profile. To assess the impact of changing technique and evolving quality assurance on genitourinary toxicity rates.

One hundred eighty patients were treated with external beam radiation therapy and high-dose-rate brachytherapy (HDRB) for localized intermediate- and high-risk prostate cancer, between December 2002 and February 2012. The HDRB technique evolved over the period of this study, from 19.5 Gy/3 (n = 68), to 17 Gy/2 (n = 40), 18 Gy/2 (n = 39), and most recently 19 Gy/2 (n = 33). In the two fraction cohort, 68 patients underwent additional correction for catheter displacement before each fraction.

With a median followup of 5.2 years, 5-year freedom from failure was 93.7% for intermediate, and 76.0% for high risk patients. The 3- and 6-year cumulative stricture incidence for all patients was 7.8% and 15.3%, respectively. There was no statistically significant difference in stricture rate for the four dose levels used nor between the three fractions and the two fraction technique overall. The 19 Gy/2 fractionation group had the lowest 3-year stricture rate (3.0%). The addition of correction for intrafraction catheter displacement did not result in a statistically significant difference in stricture rates, although the severity of strictures has been reduced.

Our biochemical control is consistent with other similar series. We found no increase in late urinary toxicity with a two fraction, two implant HDRB technique compared with three fractions. The HDRB dose did not correlate with stricture rates in our series. Correction of intra-fraction catheter displacement did not lead to a statistically significant reduction in stricture rates, although may have mitigated the effects of dose escalation.