Session Item

Sunday
November 29
16:45 - 17:45
Physics Stream 1
Proffered papers 25 - Clinical implementation of online MRgRT
2495
Proffered Papers
Physics
11:02 - 11:10
Stereotactic or conventional RT for macroscopic prostate bed recurrence: a propensity score analysis
PH-0118

Abstract

Stereotactic or conventional RT for macroscopic prostate bed recurrence: a propensity score analysis
Authors: Francolini|, Giulio(1)*[francolinigiulio@gmail.com];Jereczek-Fossa |, Barbara Alicja (2);Di Cataldo |, Vanessa(3);Simontacchi|, Gabriele(4);Marvaso|, Giulia(5);Zerella|, Maria Alessia(5);Gentile|, Piercarlo (6);Bianciardi|, Federico (6);Allegretta|, Sara (6);Detti|, Beatrice (4);Masi|, Laura (7);Ciccone|, Lucia Pia(4);Bruni|, Alessio (8);Ingrosso |, Gianluca(9);Mazzeo|, Ercole (8);Trippa |, Fabio (10);Lohr|, Frank (8);Livi|, Lorenzo (11);
(1)University of Florence- Istituto Fiorentino di Cura ed Assistenza, Radiation Oncology Unit-CyberKnife Center, Florence, Italy;(2)Department of Oncology and Hemato-oncology-University of Milan, Division of Radiotherapy- IEO European Institute of Oncology- IRCCS, Milan, Italy;(3)University of Florence - Istituto Fiorentino di Cura ed Assistenza, Radiation Oncology Unit- CyberKnife Center, Florence, Italy;(4)Azienda Ospedaliero-Universitaria Careggi, Radiation Oncology Unit, Florence, Italy;(5)IEO European Institute of Oncology- IRCCS, Division of Radiotherapy, Milan, Italy;(6)UPMC San Pietro FBF, Division Radiotherapy, Rome, Italy;(7)IFCA, Department of Medical Physics and Radiation Oncology, Florence, Italy;(8)University Hospital of Modena, Radiotherapy Unit, Modena, Italy;(9)University of Perugia and Perugia General Hospital, Radiation Oncology Section- Department of Surgical and Biomedical Sciences, Perugia, Italy;(10)"S. Maria" Hospital, Radiotherapy Oncology, Terni, Italy;(11)University of Florence, Department of Biomedical- Experimental- and Clinical Sciences “Mario Serio”, Florence, Italy;
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Purpose or Objective

Biochemical recurrence after radical prostatectomy (RP) is routinely managed with salvage radiation therapy (SRT) with curative purpose. However, patients with macroscopic local recurrence detected with positive metabolic imaging showed poor response to conventional SRT and may need treatment intensification. Dose escalated treatment may be used to achieve better disease control. Stereotactic radiotherapy for macroscopic prostate recurrence (SSRT) may be used to increase outcome in these patients, with potential advantages in terms of reduced treatment volumes and lower number of fractions. No direct comparisons between conventional prostate bed SRT and SSRT have been carried out. Thus, we retrospectively collected data from patients treated with these two approaches and compared their outcomes with a propensity score based matched analysis.

Material and Methods

Data from 185 patients treated in 6 Italian Centers for macroscopic prostate bed recurrence after RP were retrospectively collected and reported. Overall, 90 and 95 patients underwent SSRT and SRT, respectively (Fig.1). Patients in SSRT group were treated with a mean dose of 34.4 Gy (32.5-35 Gy) in 5 fractions, while patients in SRT cohort were treated with a mean dose of 72.4 Gy (60-79 Gy) in 28-38 fractions. Propensity scores were calculated for each patient using multivariate logistic models on the basis of PSA at recurrence, concomitant androgen deprivation therapy (ADT), Time to recurrence (TTR) and Gleason Score (GS). Biochemical recurrence was defined as a PSA increase above 0.2 ng/ml for patients with a PSA nadir < 0.2 ng/ml or 2 consecutive PSA increases >25% if compared to nadir in patients with a PSA nadir > 0.2 ng/ml. Cohort characteristics were compared after matching with Chi squared and Mann Whitney test to assess the distribution of baseline features in the groups.  Comparison in terms of Biochemical recurrence free survival (BRFS) was performed using analysis of covariance to take in account different extent of follow-up in the cohorts. Rate of reported genitourinary (GU) and gastrointestinal (GI) G> 2 toxicity, according to CTCAE score v.4.03 was compared with Chi-squared test.


Results

After matching, 39 and 40 patients in the SRT and SSRT groups were selected (table 1). Mean BRFS was 33.8 and 39.6 months in the SRT and SSRT groups, respectively (p=0.18). Overall, acute and late GU toxicity in the SRT versus SSRT groups was reported in 45 versus 23% (p˂0,0001) and 20 versus 5 % (p=0.04) of patients, respectively. Acute and late GI toxicity was reported in 40 versus 10.3 % (p=0.0002) and 17.5 versus 3% (p=0.002), respectively.


Conclusion

Significantly lower toxicity was observed after SSRT while maintaining the same tumour outcome, when compared to SRT. The findings of our study suggest that SSRT may be considered a valid option for post-prostatectomy macroscopic local recurrence, offering short (convenient), cost-effective, well tolerated and efficacious approach.