PSA doubling time, seminal vesicle invasion, and efficacy of salvage radiation therapy

A small study from one hospital in Norway has suggested that PSA doubling times after surgery may predict the value of salvage radiation therapy alone as a second line form of therapy.

Servoll et al. carried out a retrospective analysis of data from 76 patients treated with salvage external beam radiation therapy (EBRT) at their institution between 1987 and 2010. Prior to their salvage radiotherapy, patients were all in biochemical recurrence after an initial radical prostatectomy.

Here are the findings reported by the authors:

  • All 76 patients were treated with conformal EBRT.
    • 68/76 patients (90 percent) received a dose of 70 Gy.
    • 8/76 patients (10 percent) received a dose of 60–64 Gy.
  • None of the patients received either adjuvant or neoadjuvant androgen deprivation therapy (ADT) in conjunction with salvage EBRT.
  • Average (median) follow-up after salvage EBRT was 82 months (range, 5–192 months).
  • 17/76 patients (22 percent) exhibited biochemical recurrence after their salvage EBRT.
  • Overall actuarial rates of freedom from biochemical recurrence were
    • 84 percent at 50 months
    • 79 percent at 75 months
  • 7/76 patients (9 percent) developed metastatic disease.
  • 2/76 patients (3 percent) died of prostate cancer.
  • Independent predictors of biochemical recurrence after prostatectomy and before slavage radiation therapy were
    • Seminal vesicle invasion (SVI) in the prostatectomy specimen (p < 0.05)
    • A PSA doubling time of ≤ 6 months (p = 0.041)

What does this study tell us that is new? Probably very little beyond the fact that a PSA doubling time of ≤ 6 months is a strong indication that salvage radiation therapy with EBRT alone is not going to be able to induce a truly durable response in most men with biochemical recurrence after a radical prostatectomy. The implication is that if one wants to try salvage radiation therapy when you have a biochemical recurrence post-surgery, you can try it on its own (without any ADT) if your PSA doubling time is > 6 months but if it is ≤ 6 months you should probably try it in combination with a period of neoadjuvant and adjuvant ADT. The same seems to be true if your post-surgical recurrence is associated with the presence of seminal vesicle invasion at the time of surgery.

One the other hand, this is a small study based on data from a single institution over a long time period; it basically provides us with pilot data, and it would be nice to see confirmatory data from a much larger study of men treated consistently at a group of institutions since about 2000.

One Response

  1. My small study based on myself in the cohort, … It would be nice to see some more data on the combination of RP/ART/AHT using mpMRI as a predictor of improved success. I know that I am one, but I know a lot of guys like me. Thanks as always for the post. I don’t see any surprises here.

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