Radiotherapy in Metastatic Castration Resistant Prostate Cancer Patients with Oligo-Progression during Abiraterone-Enzalutamide Treatment: A Mono-Institutional Experience - Beyond the Abstract

Castration resistant prostate cancer patients are a niche of patients affected by progressive prostate cancer despite androgen deprivation therapy and a serum testosterone value < 50 mg/dl.

Among the six different agents’ physicians have in the quiver to use in mCPRC patients, androgen receptor targeted therapy (ARTT) has high efficacy in patients with mCRPC, leading to improved overall survival as it has been shown for abiraterone and enzalutamide in phase III clinical trials.

Starting from these points, we sought to demonstrate that treating oligo-progressive sites with radiotherapy can prolong ARTT duration in mCRPC patients.

We stratified our population analysis minding the RT treatment time start (treated < 6-month vs > 6-months from the start of ARTT), treatment RT techniques (SBRT vs. 3DRT), ARTT used as first-line vs. as second-third line, PSA reduction < 50% vs. > 50% at I follow-up. One arguing point that is a strong limitation in our analysis is its retrospective nature which can’t allow a pure statistical analysis. Perhaps, we’ll further perform a Propensity score 1–1 nearest neighbor matching without replacement when the overall population study grows up, to match treatment groups.

Observing the data currently available and examinable in literature, our study is the first, despite its retrospective nature, introducing some new variables in this asset of patients: first of all the RT treatment time start < 6 month vs >  6 months from the begin of ARTT, and moreover the comparison between two therapeutic lines that stands still not explored by any other author.

In fact, analyzing the survivals with the stratification factors before mentioned, there was a trend toward a better OS in patients that received radiotherapy 6  months after the start of ARTT vs. before 6  months (median OS 46.6 months vs. 37.5 months; p = 0.101) and a significant difference in term of PFS (median PFS 27.7 months vs 7.9 months; p < 0.001).

Written by: Maurizio Valeriani, Luca Marinelli, Serena Macrini, Chiara Reverberi, Anna Maria Aschelter, Vitaliana De Sanctis, Paolo Marchetti, Lidia Tronnolone, Mattia Falchetto Osti

Department of Radiation Oncology, "Sapienza" University, Sant'Andrea Hospital, Rome, Italy., Department of Radiation Oncology, "Sapienza" University, Sant'Andrea Hospital, Rome, Italy., Department of Oncology, "Sapienza" University, Sant'Andrea Hospital, Rome, Italy.

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