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26-09-2011 | Endocrinology | Article

Model predicts likelihood of erectile dysfunction after prostate therapy


Free abstract

MedWire News: Researchers have devised a model to predict the likelihood of future erectile dysfunction among men about to undergo treatment for prostate cancer.

The model is based on pretreatment patient characteristics and treatment details and was validated in an independent longitudinal cohort.

Study co-author Martin Sanda (Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA) said that such a prediction "is pivotal to set appropriate expectations and facilitate medical decision-making."

Improved survival in early-stage prostate cancer has meant health-related quality of life (HRQoL) outcomes have emerged as a major emphasis in treatment decisions. Erectile dysfunction in particular is common after prostate cancer treatment and has significant consequences for HRQoL; however, it is currently difficult to predict the chance it will actually arise.

In the current study, the researchers identified 1027 patients scheduled to undergo prostatectomy, external radiotherapy, or brachytherapy for prostate cancer. Information was gathered in terms of pretreatment patient characteristics, sexual HRQoL, and treatment details.

The team interviewed patients at 2 years of follow-up, focusing on patient-reported ability of achieving erections sufficient for intercourse - based on the response to question 26 on the expanded prostate cancer index composite-26 questionnaire.

This was chosen, rather than evaluating total HRQoL score, as the endpoint "to provide a concrete metric having practical relevance to routine clinical care," say the researchers.

Sanda et al report that 368 (37%) of all patients and 335 (48%) of those with functional erections prior to treatment reported functional erections at follow-up. The rate of functional erections in the specific treatment groups was 35% for men who underwent prostatectomy, 37% for those undergoing external radiotherapy, and 43% for men who received brachytherapy as primary treatment.

Using this information the researchers devised logistic regression models in an attempt to predict erectile function at 2 years. This yielded probabilities from as low as 10% or less, to as high as 70% or greater, depending on the individual's pretreatment patient characteristics and treatment details.

Sanda et al then sought to validate these models in a separate cohort of 1913 men due to undergo treatment for prostate cancer.

The models performed well in predicting functional erections suitable for intercourse 2 years after treatment, with an area under the receiver operating characteristic curve score of 0.77 for men undergoing prostatectomy, 0.87 for those undergoing external radiotherapy, and 0.90 for those undergoing brachytherapy.

Sanda et al comment: "Measuring sexual HRQoL at the point of care with the Expanded Prostate cancer Index Composite 26 (EPIC) may be cumbersome and could impede use of our findings in routine practice.

"To address this barrier (separately from this study), we have developed the EPIC for Clinical Practice, a one-page HRQoL questionnaire that can be completed in 5 minutes and allows HRQoL scores to be easily calculated by clinicians at the point of care."

By Andrew Czyzewski

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