It may be possible to better predict biochemical recurrence (BCR) after primary whole gland cryotherapy for prostate cancer (PCa), according to Canadian researchers.1

They identified several robust disease-specific and early postoperative predictors of BCR. They hypothesize that these risk factors may be useful when counseling men prior to cryoablation. 

Adam Kinnaird, MD, PhD, of the University of Alberta in Edmonton, and colleagues explained that multiple randomized clinical trials have demonstrated similar rates of BCR with primary whole gland cryotherapy compared with radiation therapy and several studies have examined risk factors of BCR after radical prostatectomy (RP). However, few data are available on men undergoing primary whole gland cryotherapy.

Dr Kinnaird’s team conducted a retrospective analysis of 350 patients who received primary whole gland cryotherapy from 2007 to 2017 at a single large tertiary referral center. The primary outcome for this investigation was BCR, defined by Phoenix criteria (PSA nadir + 2.0 ng/mL). At a median follow-up of 38.6 months, BCR occurred in 119 patients (34%).

Older age and high- and very high-risk disease, as defined by National Comprehensive Cancer Network (NCCN) criteria, were independently associated with an increased risk of BCR. Each 1-year increment in age was significantly associated with a 5% increased risk. High-risk and very high-risk disease were significantly associated with a 12- and 15-fold greater risk.

 “Most importantly, our statistical modelling identified a post-ablative PSA nadir of 0.7 [ng/mL] or greater to be the ideal threshold to predict biochemical failure,” Dr Kinnaird told Renal & Urology News. “Patients with a PSA nadir of 0.7 or greater were over 4 times more likely to have biochemical failure than those patients with a PSA nadir less than 0.7.”

Approximately 75% of patients with a PSA nadir above this threshold had biochemical recurrence within 3 years, the investigators reported. He and his colleagues now are using these results when counseling their high-risk patients. They also have modified their clinical practice to frequently monitor serum PSA for at least the first 3 years in patients with a nadir greater than 0.7.

Christopher Saigal MD, MPH, Professor and Vice Chair of Urology at the UCLA School of Medicine said the findings are reasonable in that the NCCN risk criteria functioned appropriately in predicting outcome. Documentation of a binary cutoff for PSA nadir could be helpful in patient counseling and post-treatment surveillance, Dr Saigal said. “Of course, prostate cancer outcomes are thought to mature over a 10 year period, so the outcomes here may worsen significantly over time, or result in a change in the nadir value of interest,” he said. “These PSA recurrence outcomes should be considered in tandem with the quality of life outcomes that correspond to whole gland cryotherapy, surgery, and radiation therapy.”

David Y Chen, MD, a professor in the Department of Surgical Oncology and the Director of the Urologic Oncology Fellowship Program at Fox Chase Cancer Center, Philadelphia, said the accepted treatment options for men with localized PCa include RP, radiotherapy, or whole gland cryoablation. Use of cryotherapy, however, is limited, and in prior assessments, primary cryoablation accounted for less than 4% men who receive definitive treatment.

“As it is an infrequently applied therapy, there is limited information on comparative effectiveness between primary whole gland cryotherapy and other modalities of treatment, whereas robust data has been reported comparing outcomes of prostatectomy and radiation treatment,” Dr. Chen said. “This study importantly begins to establish the criteria that might predict the outcome for men treated by primary cryotherapy, suggesting which men may have a higher odds of incomplete treatment and prostate cancer recurrence following treatment.”

Recognizing parameters that predict a higher likelihood of recurrence is important for guiding clinicians and patients in their decision-making, and this new information may sway those men at higher odds of treatment failure away from primary cryotherapy and towards alternative treatment options, he said.

Neil Desai, MD, Assistant Professor of Radiation Oncology at the University of Texas Southwestern Medical Center in Dallas, said men with localized disease now are benefiting from improved surgical techniques and a multitude of radiation options each adapted to patient specific features. “Thus, I am certainly biased to long-term data, particularly for higher risk patients, who almost always require multimodal therapy and for whom cryotherapy’s role is largely unvetted,” Dr Desai said. “Thus, this study’s finding of frequent and rapid recurrence in higher risk disease with cryotherapy strongly argues for either similar multi-modal strategies added to cryotherapy or avoiding cryotherapy altogether in these patients.”

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Reference

Kinnaird A, McLarty R, Bain A, et al. Predictors of biochemical recurrence after primary whole gland cryotherapy for prostate cancer. Presented at the American Urological Association’s 2019 annual meeting held May 3-6 in Chicago. MP78-02. doi:10.1097/01.JU.0000557334.94208.3f