Hypothesis / aims of study
Alpha1-adrenceptor antagonists are commonly used to manage lower urinary tract symptoms (LUTS) experienced by men receiving radiotherapy for localised prostate cancer. There is evidence that some alpha1-adrenoceptor antagonists such as prazosin, reduce the incidence of prostate cancer and increase apoptosis in the prostate compared to unexposed men [1, 2]. Several in vitro studies have also demonstrated cytotoxic actions of quinazoline alpha1-adrenceptor antagonists in prostate cancer cell lines, an effects that is independent of alpha-adrenoceptor blockade . These cytotoxic actions are not observed with the non-quinazoline antagonist tamsulosin. The potential dual LUTS and anti-cancer actions of these antagonists may be particularly beneficial in men treated with radiotherapy for localised prostate cancer. The aim of this study was to determine if the quinazoline alpha1-adrenceptor antagonist prazosin and the non-quinazoline antagonist tamsulosin delay time to biochemical relapse and influence recurrence in men with prostate who have received radiotherapy as part of their treatment regimen.
Study design, materials and methods
We retrospectively evaluated data from 303 men with histologically proven adenocarcinoma of the prostate who received radiotherapy between 1998 and 2017. The medical records database was first refined to identify patients who had been treated with either prazosin (n=147) or tamsulosin (n=72), while men naive to alpha1-ADR antagonists were used as a control (n=84) group for comparison. Baseline demographic characteristics including age at diagnosis, Gleason score, tumour staging and any treatment modalities were collected. PSA values were recorded periodically from diagnosis up to 120 months (10 years) if available. Two primary outcomes were evaluated including relapse rates (%) at two and five years and time to biochemical relapse (months). Recurrence free survival (%) was also calculated using Kaplan Meier curves.
Interpretation of results
Exposure to the quinazoline alpha1-ADR antagonist prazosin, reduces the risk of prostate cancer recurrence and delays time to biochemical relapse. Although tamsulosin delayed time to biochemical relapse, there was no effect on two and five-year relapse rates.