On 2014 Feb 19, Francesca Demichelis commented:

Thank you for your comment. The yearly brachytherapy accrual rate at the study site is ~50. The number of patients included in the study was limited by tissue availability for biomarker assays. The 2000-2008 average postplanning values for V100 and D90 (at one month) were 93% and 158 Gy, respectively. Therefore, it is the molecular stratification of prostate cancer in these patients which may explain the high failure rate in a predominantly low-risk population, not the dosimetry. The significance of the molecular alterations in this setting needs to be tested by independent studies.

On 2014 Feb 12, Wayne Butler commented:

The regression did not account for prostate dosimetric quality parameters such as D90 and V100. An 11% failure rate in a predominantly low-risk population is very high, so poor quality implant dosimetry is probably a major factor. Their accrual rate of about 10 brachytherapy patients per year is well below the threshold necessary to become proficient in the operative procedure. It would be simple to compare mean dosimetry parameters between failures and non-failures, but that crucial data was not part of the analysis, so it remains unknown whether molecular alterations would remain as an independent predictor.

On 2014 Feb 12, Wayne Butler commented:

The regression did not account for prostate dosimetric quality parameters such as D90 and V100. An 11% failure rate in a predominantly low-risk population is very high, so poor quality implant dosimetry is probably a major factor. Their accrual rate of about 10 brachytherapy patients per year is well below the threshold necessary to become proficient in the operative procedure. It would be simple to compare mean dosimetry parameters between failures and non-failures, but that crucial data was not part of the analysis, so it remains unknown whether molecular alterations would remain as an independent predictor.