A pretreatment nomogram predicting biochemical failure after salvage cryotherapy for locally recurrent prostate cancer

Abstract

Objective: To gather a pooled database from six tertiary-care referral centres using salvage cryotherapy (SC) for locally recurrent prostate cancer, and develop a pretreatment nomogram allowing a prediction of the probability of biochemical failure after SC, based on pretreatment clinical variables.

Patients and methods: We retrospectively analysed 797 men treated at six tertiary-care referral centres with SC for locally recurrent disease after primary radiotherapy with curative intent. The median duration of follow-up from the time of SC to the date of last contact was 3.4 years. The primary study endpoint was biochemical failure, defined as a serum prostate-specific antigen (PSA) level after SC of >0.5 ng/mL.

Results: Overall, the rate of biochemical failure was 66% with a median of 3.4 years of follow-up. A logistic regression model was used to predict biochemical failure. Covariates included serum PSA level at diagnosis, initial clinical T stage, and initial biopsy Gleason score. On the basis of these results, a pretreatment nomogram was developed which can be used to help select patients best suited for SC. Our pretreatment nomogram was internally validated using 500 bootstrap samples, with the concordance index of the model being 0.70.

Conclusion: A pretreatment nomogram based on several diagnostic variables (serum PSA level at diagnosis, biopsy Gleason grade, and initial clinical T stage) was developed and might allow the selection of ideal candidates for SC.