Alejandro Berlin1, Ardalan E Ahmad2, Melvin L K Chua3, Fabio Y Moraes4, Haiyan Jiang5, Maria Komisarenko2, Narhari Trimilshina2, Hamid Raziee4, Ali Hosni4, Jure Murgic4, Peter Chung4, Robert G Bristow4, Antonio Finelli6. 1. Radiation Medicine Program, Princess Margaret Cancer Centre-University Health Network, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada. Electronic address: alejandro.berlin@rmp.uhn.ca. 2. Division of Urology, Department of Surgical Oncology, Princess Margaret Cancer Centre-University Health Network, University of Toronto, Toronto, Ontario, Canada. 3. Radiation Medicine Program, Princess Margaret Cancer Centre-University Health Network, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada; Division of Radiation Oncology, National Cancer Centre Singapore, Singapore. 4. Radiation Medicine Program, Princess Margaret Cancer Centre-University Health Network, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada. 5. Department of Biostatistics, Princess Margaret Cancer Centre-University Health Network, Toronto, Ontario, Canada. 6. Division of Urology, Department of Surgical Oncology, Princess Margaret Cancer Centre-University Health Network, University of Toronto, Toronto, Ontario, Canada. Electronic address: Antonio.Finelli@uhn.ca.
Abstract
PURPOSE: To describe and compare outcomes in men with initially presumed indolent prostate cancer receiving definitive radiation therapy after active surveillance (AS) versus those in a risk-matched cohort undergoing up-front radiation therapy. METHODS AND MATERIALS: Men prospectively enrolled in an AS program between 1992 and 2014 and subsequently undergoing curative radiation therapy (ie, image guided radiation therapy [IGRT] or low-dose-rate brachytherapy [LDR-BT]) were identified. Biochemical relapse-free rate (bRFR), metastasis-free rate (mFR), and overall survival (OS) were compared against a cohort of men treated up front, matched by age, clinical prognostic indices (risk group, prostate-specific antigen, cT category, Gleason score, percentage of involved biopsy cores), and radiation therapy modality. RESULTS: Of 1070 patients in the AS registry, 200 underwent definitive radiation therapy (143 IGRT and 57 LDR-BT) after a median of 32.9 (interquartile range [IQR] 20.6-59.8) months on surveillance. Main reasons for treatment were grade and volume upgrading (57.5% and 26%, respectively). Median follow-up after radiation therapy was 4.9 (IQR 3.1-7.5) years. At 5 years the bRFR, mFR, and OS were, respectively, 97%, 99%, and 98.5%. No patient died of prostate cancer. Adequate risk-matching was confirmed in an independent cohort comprising 359 patients receiving up-front IGRT (71%) or LDR-BT (29%) and followed for a median of 9 (IQR 3.1-7.5) years. There was no difference in the disease-specific outcomes (bRFR, mFR) between the 2 cohorts (Gray's P value of .257 and .934, respectively). In multivariate analyses, timing of radical radiation therapy (deferred vs up-front) was not correlated to biochemical relapse or metastases occurrence. CONCLUSIONS: Curative-intent radiation therapy (ie, dose-escalated IGRT or LDR-BT) after a period of AS renders excellent oncologic outcomes at 5 years. Deferring radical therapy after a period of AS does not seem to result in inferior oncologic outcomes compared with patients with similar risk characteristics undergoing up-front treatment.
PURPOSE: To describe and compare outcomes in men with initially presumed indolent prostate cancer receiving definitive radiation therapy after active surveillance (AS) versus those in a risk-matched cohort undergoing up-front radiation therapy. METHODS AND MATERIALS: Men prospectively enrolled in an AS program between 1992 and 2014 and subsequently undergoing curative radiation therapy (ie, image guided radiation therapy [IGRT] or low-dose-rate brachytherapy [LDR-BT]) were identified. Biochemical relapse-free rate (bRFR), metastasis-free rate (mFR), and overall survival (OS) were compared against a cohort of men treated up front, matched by age, clinical prognostic indices (risk group, prostate-specific antigen, cT category, Gleason score, percentage of involved biopsy cores), and radiation therapy modality. RESULTS: Of 1070 patients in the AS registry, 200 underwent definitive radiation therapy (143 IGRT and 57 LDR-BT) after a median of 32.9 (interquartile range [IQR] 20.6-59.8) months on surveillance. Main reasons for treatment were grade and volume upgrading (57.5% and 26%, respectively). Median follow-up after radiation therapy was 4.9 (IQR 3.1-7.5) years. At 5 years the bRFR, mFR, and OS were, respectively, 97%, 99%, and 98.5%. No patient died of prostate cancer. Adequate risk-matching was confirmed in an independent cohort comprising 359 patients receiving up-front IGRT (71%) or LDR-BT (29%) and followed for a median of 9 (IQR 3.1-7.5) years. There was no difference in the disease-specific outcomes (bRFR, mFR) between the 2 cohorts (Gray's P value of .257 and .934, respectively). In multivariate analyses, timing of radical radiation therapy (deferred vs up-front) was not correlated to biochemical relapse or metastases occurrence. CONCLUSIONS: Curative-intent radiation therapy (ie, dose-escalated IGRT or LDR-BT) after a period of AS renders excellent oncologic outcomes at 5 years. Deferring radical therapy after a period of AS does not seem to result in inferior oncologic outcomes compared with patients with similar risk characteristics undergoing up-front treatment.