Nadir PSA is a strong predictor of treatment outcome in intermediate and high risk localized prostate cancer patients treated by definitive external beam radiotherapy and androgen deprivation

The aim of this study is to investigate the effect of tumor characteristics and parameters of treatment response in predicting biochemical disease-free survival (BFS) for patients with intermediate or high risk prostate cancer treated by combined definitive external beam radiation therapy (EBRT) and androgen deprivation therapy (ADT).

Between June 1995 and January 2015, 375 patients with localized prostate cancer and a National Comprehensive Cancer Network (NCCN) intermediate or high risk categories were treated by definitive EBRT and ADT. Median duration of androgen blockade was 10 months (range: 3-36 months); Median radiation dose was 72 Gy (Range: 70-78 Gy). Median follow-up time was 5.8 years (range: 0.8-16.39 years). The main study endpoint was biochemical disease free survival (BFS).

Forty seven patients (12.5%) developed biochemical recurrence (BCR) during the observation period. Monovariate analysis identified baseline PSA (bPSA) (p = 0.024), T-stage (p = 0.001), Gleason's score (GS) (p = 0.042), radiation dose (p = 0.045), PSA pre-radiation therapy (p = 0.048), and nadir PSA (nPSA), (p < 0.001) as significant variables affecting BCR. The receiver operating characteristic (ROC) curve identified a nPSA of 0.06 ng/ml as optimal cut-off value significantly predicting the patients' risk of BCR (p < 0.001). Multivariate cox regression analysis revealed T-stage, GS, and nPSA as independent variable affecting BFS, while bPSA, age, and radiation dose were not.

Nadir PSA at 0.06 is a strong independent predictor of BFS in patients with intermediate or high risk prostate cancer treated by definitive EBRT and ADT.

Radiation oncology (London, England). 2017 Sep 07*** epublish ***

Fady B Geara, Muhammad Bulbul, Raja B Khauli, Therese Y Andraos, Mirna Abboud, Abdelatif Al Mousa, Nasim Sarhan, Ahmed Salem, Hamza Ghatasheh, Anoud Alnsour, Zeina Ayoub, Ibrahim Abu Gheida, Maya Charafeddine, Mohammed Shahait, Ali Shamseddine, Rami Abu Gheida, Jamal Khader

Department of Radiation Oncology, The Naef K. Basile Cancer Institute at the American University of Beirut Medical Center, Bliss Street, Riad El Solh, Beirut, 11072030, Lebanon. ., Division of Urology, the American University of Beirut Medical Center, Beirut, Lebanon., Department of Radiation Oncology, The Naef K. Basile Cancer Institute at the American University of Beirut Medical Center, Bliss Street, Riad El Solh, Beirut, 11072030, Lebanon., Department of Radiation Oncology, King Hussein Cancer Center, Amman, Jordan., Division of Medical Oncology, The Naef K. Basile Cancer Institute at the American University of Beirut Medical Center, Beirut, Lebanon.

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