MP48-09: Toxicity profile of immediate post-prostatectomy radiation therapy: results from a large multi-institutional series

Nicola Fossati*, Lugano, Switzerland, Jeffrey R. Karnes, Stephen A. Boorjian, Alberto Bossi, Rochester, MN, Nadia Di Muzio, Cesare Cozzarini, Barbara Noris Chiorda, Giorgio Gandaglia, Milano, Italy, Detlef Bartkowiak, Ulm, Germany, Shahrokh Shariat, Vienna, Austria, Gregor Goldner, Department of Radiation Oncology, Austria, Charlien Berghen, Steven Joniau, Gert De Meerleer, Leuven, Belgium, Elio Mazzone, Armando Stabile, Milano, Italy, Hendrik van Poppel, Leuven, Belgium, Andrea Gallina, Lugano, Switzerland, Francesco Montorsi, Milano, Italy, Thomas Wiegel, Ulm, Germany, Alberto Briganti, Milano, Italy

Introduction: Immediate post-operative radiation therapy (RT) has shown improved oncological outcomes in patients with adverse pathological features and/or prostate-specific antigen (PSA) persistence after radical prostatectomy (RP). Although post-operative RT represents an established risk factor for decreased quality of life, little is known about specific toxicity profiles and their related predictors. We aimed at reporting the results from a large series of patients treated with post-operative RT

Methods: The study included 319 patients who received immediate post-operative RT (within six months after RP) at six institutions. Concomitant hormonal therapy (HT), radiation dose, and radiation field were left at the discretion of the treating physician. Acute (=1yr) and late (>1yr) radio-induced genitourinary (GU) and gastrointestinal (GI) complications were classified according to the RTOG/EORTC scoring system. Severe toxicity was defined as any complication with grade =2. Multivariable logistic regression analysis was used to identify predictors of severe complications. Covariates consisted of age at RT, time from RP to RT, concomitant HT, RT dose, and RT field

Results: Overall, 164 (52%) patients were treated for adverse pathological features, whereas 155 (48%) for PSA persistence (>0.1 ng/ml) after RP. Concomitant HT was administered to 184 (58%) patients, for a median duration of 24 months. The median dose was 66 Gy. Whole pelvis RT was administered to 184 (58%) patients. Acute GU, acute GI, late GU and late GI toxicities were reported in 170 (53%), 207 (65%), 147 (46%) and 99 (31%) patients, respectively. Severe toxicity distribution was the following: 49 (15%) acute GU, 91 (29%) acute GI, 81 (25%) late GU, and 41 (13%) late GI. At multivariable analysis, time from RP to RT was inversely associated with all type of severe complications: acute GU (OR: 0.67; p=0.012), acute GI (OR: 0.73; p=0.010), late GU (OR: 0.65; p=0.003), and late GI (OR: 0.79; p=0.012). Moreover, RT dose was a significant predictor of severe acute GU (OR: 1.16; p=0.006), whereas RT field was significantly associated with severe acute GI (OR: 3.27; p=0.002) complications

Conclusions: A significant proportion of men developed severe complications when treated with immediate post-operative RT. Our data suggest that – even in a short interval of six months – time from surgery to RT is the most significant predictor of severe toxicity. Delaying radiation treatment for a few months, even in the setting of adjuvant treatments, may dramatically decrease the risk of severe complications

Source of Funding: none