When men are diagnosed with prostate cancer, their first task, and what might be their hardest task is to decide what treatment they want to utilize. Men who cannot use active surveillance (AS) usually need to choose between the surgical removal of their prostate gland (radical prostatectomy, RP) or local radiation therapy (RP).
An abstract presented from the virtual meeting of the American Urological Association (AUA) compared surgery (RP) to radiation (RT) as primary treatment for prostate cancer. It found that surgery may result in a lower risk of castration-resistant disease and superior overall survival (OS) from the time of metastasis.
In this retrospective analysis of a nationwide database of men who had undergone prior radiation or surgery for localized prostate cancer, those who received radiotherapy were found to have a 32% higher risk of developing a castration-resistant state than those having surgery. These results were reported by Mohammed Shahait, MBBS, who was a clinical instructor in urology at the University of Pennsylvania in Philadelphia, at the time of the study. These study results were reported in a poster presented at the American Urological Association 2020 Virtual Experience.
The findings come from an examination of the Flatiron Health electronic health record–derived database, which includes about 2.5 million patients with cancer.
In an attempt to make a homogenous study cohort Shahait used a cohort that consisted of 664 men who had received surgery (RP) with or without adjuvant radiation (n = 310) or radiation therapy (RT) alone (n = 354) for local disease and had progressed to metastatic disease between 2010 and 2018.
At the time when the study group developed metastasis, men in the surgical group (RP) were younger, had a lower prostate-specific antigen (PSA) level at prostate cancer diagnosis (7.8 vs 10.9 ng/mL; P <.0001), and were more likely to have a Gleason score greater than or equal to 8 (64.5% vs. 54.5%; P = .0089). The men in the radiation group (PR) also had lower PSA levels at the time of metastasis compared with those in the radiation group (6.4 vs. 17.2 ng/mL; P <.0001). The group treated with radiation was more likely to receive androgen-deprivation therapy (ADT) before metastasis compared with the RP group (76% vs. 60.7%; P <.0001).
On multivariable analysis, men who received radiation alone had 77% higher overall mortality after developing metastatic disease (P = .0013) compared with men who underwent RP.
Notwithstanding the inherent selection bias when choosing the type of local treatment because of unmeasured confounding variables, the results add to a growing body of evidence that supports the benefit of extirpation of the primary disease on OS after developing metastatic disease, the researchers concluded in their poster.
One theory for the finding is that early use of ADT and RT may potentiate epithelial-mesenchymal transition, which mediates tumor invasion, metastasis, and development of castration-resistant tumors, leading to a worse outcome, Shahait said.
May 13, 2020 AUA Annual Meeting
