916P - c-MYC Expression is Modulated by Statins Use and it's Correlated with Time to Progression (TTP) in Men with Localised Prostate Cancer Treated with Radical Radiotherapy

Abstract

ABSTRACT Background Although statins do not affect the incidence of prostate cancer (PCa), its use reduces the risk of clinical progression and mortality. The mechanism by which statins reduce PCa progression is unknown. MYC phosphorylation is a critical mechanism by which the inhibition of HMG-CoA reductase by statins, thereby resulting in MYC dephosphorylation and inactivation, which is essential for their anticancer therapeutic effect. The aim of this study was to correlate statins use with the c-MYC levels in PCa patients treated with radical radiotherapy (RT) with concurrent androgen deprivation. Methods A total of 85 patients with paraffin-embedded prostate tissue specimens were investigated immunohistochemically for c-MYC overexpression, diagnosed with PCa between 2000 and 2005. Clinical and pathological variables were compared between statin users and non-users and correlates with expression of c-MYC. Disease-free survival (DFS) and time to progression (TTP) were analysed. Results Mean age was 71 (56-82) years and median follow-up was 75 months. Three (3.5%), 14 pts (16.5%) and 68 pts (80%) were classified as low, medium and high risk respectively. Of those, 20 patients (24%) were using statins, either during initial consultation or during follow-up. No statistical differences were found between treatment groups regarding median age, risk category, clinical T stage, Gleason score or median radiation dose. Median percentage value of c-MYC was 20 (5-80) of statin users vs. 35 (5-100) of non-users (p = 0.057) and elevated c-MYC expression was not significantly associated with shorter DFS (p = 0.5). At the time of analysis, only 13 pts (15.3%) had biochemical relapse (1 low risk, 3 intermediate, and 9 high risk). Statins use (38%) was significantly associated with improved TTP (55.2 vs. 30.6 months, p = 0.016). Conclusions In our analysis, statins use was associated with a significant improvement in TTP, in all risk groups. Although no differences in DFS according cMYC values, there is a tendency towards a lower expression in statins users. Our findings warrant further investigation. Disclosure All authors have declared no conflicts of interest.