Brachyboost and PSA progression free survival question

[EvFC]

We just received our appointment summary from the radiation oncologist and there is a comment in it that is confusing me. It’s not how I remember the conversation, so I am wondering if someone can clarify ( Tall_Allen ?).

”We can proceed with EBRT followed by LDR brachytherapy boost and minimum 6 months of ADT (as per Japanese randomized trial (IJRPBP 2023), where 6 months vs 24 months of hormones together with EBRT prostate brachytherapy boost in high risk patients yield completely the same results). PSA progression free survival as per Japanese trial as well as ASCENDE RT Canadian trial for this particular scenario is about 10-15% at 10 years.”

The progression free survival rate seems very low at 10 years. I thought it was much higher and that this was the reason for people recommending brachytherapy boost for high risk over surgery. Is this a typo or is this the case? I will probably reach out tomorrow to clarify with her office if I can, but curious if anyone knows the answer.

Thank you!

[Tall_Allen]

IDK which Japanese trial you're talking about. It helps if you provide the link.

In ASCENDE-RT the 7-year bRFS for high-risk patients for LDR-BBT was 83%:

prostatecancer.news/2016/08...

In TROG 01/03 RADAR, the 10-yr distant progression-free survival for unfavorable-risk patients for HDR-BBT was 80%:

prostatecancer.news/2020/04...

[EvFC in reply to Tall_Allen]

Thank you. Those were her notes and she didn’t provide the details of the study. My recollection was that recurrence rate was around 15% so your stats make more sense to me. Appreciate your response.

[maley2711 in reply to Tall_Allen]

What is your view on the efficacy of focal boost for appropriate patients? RO feels it could provide results approaching those with brachy boost, but better toxicity profile? Also, instead of fiducials, will use calcium deposits to help with daily alignments over 28 sessions. Apparently an option would have been traveling 700 miles to have brachy at Kaiser NoCal. Right now , 28 sessions of WPRT with focal boost to PIRADS 5 area transition zone. Younger RO MIT grad and Harvard -trained.....knows Kishan " smart guy". No luck selling him on E2 low dose patches tohelp with osteopenic situation.

[Tall_Allen in reply to maley2711]

Boost areas of known cancer either way.

[Justfor_]

It is a "reversal" kind of typo.

Wrote: "progression free survival" where the Japanese trial's primary endpoint was "cumulative incidence of biochemical progression "

"Methods and materials: This study was conducted at 37 hospitals on men aged 40 to 79 years, with stage T2c-3a, prostate-specific antigen >20 ng/mL, or Gleason score >7, who received 6 months of ADT combined with iodine-125 brachytherapy followed by EBRT. After stratification, patients were randomly assigned to either no further treatment (short arm) or 24 months of adjuvant ADT (long arm). According to the Phoenix definition of failure, the primary endpoint was the cumulative incidence of biochemical progression. Secondary endpoints included clinical progression, metastasis, salvage treatment, disease-specific mortality, overall survival, and grade 3+ adverse events. An intention-to-treat analysis was conducted using survival estimates determined using competing risk analyses.

Results: Of 332 patients, 165 and 167 were randomly assigned to the short and long arms, respectively. The median follow-up period was 9.2 years. The cumulative incidence of biochemical progression at 7 years was 9.0% (95% CI, 5.5-14.5) and 8.0% (4.7-13.5) in the short and long arms, respectively (P = .65). The outcomes of secondary endpoints did not differ significantly between the arms. Incidence rates of endocrine- and radiation-related grade 3+ adverse events for the short versus long arms were 0.6 versus 1.8% (P = .62) and 1.2 versus 0.6% (P = .62), respectively."

sciencedirect.com/science/a...

Additional info here:

ascopost.com/issues/march-2...

[EvFC in reply to Justfor_]

Thank you. This is more in line with what I remember from our conversation with her. Thank you for providing the links to the study. I appreciate your response.

[RugbyVLS]

As a side note, our RO, Dr Kishan feels that ultrahypofractionated radiation (SBRT) is equivalent to traditional IMRT plus brachytherapy boost.