Time-related loss of erectile function after low-dose-rate brachytherapy

It has long been understood that erectile function after first-line treatment for localized prostate cancer is affected by (a) erectile function before treatment and (b) elapsed time after treatment. However, the available data offering a careful analysis of the chronology of erectile function after first-line treatment of localized prostate cancer has been limited.

Bannowsky et al. have now published data on the erectile function of a small group of patients, all initially treated with low-dose rate prostate (LDR) brachytherapy, at baseline and then at up to 3 years post-treatment.

None of their patients received either supplemental external beam radiation therapy (EBRT) or any form of hormonal therapy, so we can be clear that the effects reported reflect only the impact of treatment and increasing patients age over time. In addition, none of these patients reported use of either drugs like Viagra (PDE-5 inhibitors) or intracavernosal injection therapy.

A standardized, validated questionnaire (the International Index of Erectile Function or IIEF questionnaire) was used to assess the patients’ erectile and sexual function at baseline and at 12, 24, and 36 months post-brachytherapy.

Here is a summary of the findings:

  • A total of 32 patients were treated and invited to participate in the assessment.
  • The average (median) age of the patients was 74 years (range, 65 to 83 years) at time of treatment.
  • 26/32 patients actually provided complete data appropriate for analysis.
  • 15/26 patients (58  percent) had no erectile dysfunction (ED) (score, 22 to 25) or only mild ED (score, 17 to 21) prior to treatment.
  • 11/26 patients (42 percent) had  moderate or severe ED (score, 0 to 16) prior to treatment.
  • At baseline, before seed implantation, the average (mean) IIEF score was 14.4.
  • The overall average (mean) IIEF score decreased after treatment:
    • By 4.4 points at 12 months post-treatment
    • By 3.1 points at 24 months post-treatment
    • By 9.8 points at 36 months post-treatment
  • Among the men with no or only mild ED at baseline, the average (mean) IIEF score dropped by 9.7 points at 3 years post-treatment.
  • Among the men with moderate or severe ED at baseline, the average (mean) IIEF score dropped by only 1.4 points at 3 years post-treatment.

Not surprisingly, the greatest loss in erectile function over time occurred in those men who claimed to have good or excellent erectile function prior to their treatment. However, it is worth noting a number of factors in assessing these results:

  • This was a relatively elderly cohort of patients, with an average age of 77 years at 3 years post-brachytherapy.
  • The ability and willingness of men to admit to ED before their treatment may be less than their ability to do so afterward — when they can use treatment as a justification for their loss of erectile function. (We males are all just human, after all.)
  • There is no way to know from this study what degree of loss of erectile function would have occurred over this time period as a consequence of aging alone.

Bannowsky et al. are to be congratulated for a serious attempt to assess the chronological impact of LDR brachytherapy alone on erectile function in a well-defined group of their patients. However, it is hard to know exactly how to interpret these data in a way that would be applicable to a cohort of younger men who might reasonably expect to be able to regain good erectile function for a period of time after first-line treatment for localized prostate cancer.

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