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ESTRO 36
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S. Ken
1
, F. Arnaud
1
, R. Aziza
2
, D. Portalez
2
, B. Malavaud
3
,
J. Bachaud
4
, P. Graff-Cailleaud
4
, S. Arnault
5
, A. Lusque
5
,
T. Brun
1
1
Institut Universitaire du Cancer - Oncopole - Institut
Claudius Regaud, Medical Physics and Engineering,
Toulouse, France
2
Institut Universitaire du Cancer - Oncopole - Institut
Claudius Regaud, Radiology, Toulouse, France
3
Institut Universitaire du Cancer - Oncopole - CHU de
Toulouse, Urology, Toulouse, France
4
Institut Universitaire du Cancer - Oncopole - Institut
Claudius Regaud, Radiotherapy, Toulouse, France
5
Institut Universitaire du Cancer - Oncopole - Institut
Claudius Regaud, Bureau des Essais Cliniques, Toulouse,
France
Purpose or Objective
Focal brachytherapy is proposed in our institute as an
alternative treatment to active surveillance for low-grade
prostate cancer (PCa). This study aims at characterizing
the tumor focus and its margin with multiparametric
Magnetic Resonance Imaging (mpMRI) in order to prepare
the clinical protocol of focal brachytherapy.
Material and Methods
Patients pre-qualified for this study were positive for PCa
(Gleason 3+3) on a previous standard biopsy series. New
series of mp-MRI-guided and ultrasound-targeted biopsies
were performed and in total, 17 patients with confirmed
tumor and diameter<20mm were included in this phase II
clinical trial (NCT01902680). mpMRI were acquired on a
1.5T Magnetom Aera Siemens scanner with 18-channel
surface body coil. Anatomic imaging consists in Fast Spin
Echo T2-weighted MRI (T2-MRI). In addition, same in-
plane acquisition of functional Diffusion Weighted MRI
(DWI-MRI) and Dynamic Contrast Enhanced MRI (DCE-MRI)
were performed.
After mpMRI registration, tumor volumes of interest (VOI)
were drawn on anatomic T2-MRI. VOI and VOI+2mm were
reported on functional DWI-MRI and DCE-MRI (Figure 1).
Extracted parameters were Apparent Diffusion Coefficient
(ADC) and KTrans. All parameters distributions were
analyzed with Olea Sphere v3.0 and compared to
contralateral normal appearing tissue.
Focal brachytherapy was then delivered to all patients
with linked
125
I seeds with a dose prescription of 152 Gy on
the Planning Target Volume (PTV=VOI+2mm).
Results
ADC parameters (mean, median, 25th and 75th
percentiles) are found to be significantly lower in tumor
volume (VOI) compared to contralateral normal tissue
(p<0.012 for all ADC parameters), confirming diffusion
tumor mass restriction. Different distributions of ADC and
Ktrans were observed among patients (Figure 2). Majority
(66.66%) of low ADC and abnormal Ktrans values were
included in the VOI. Interestingly, the 2mm margin allows
us to treat additional abnormal ADC and KTrans volumes
on 1/3 of the patients.
Conclusion
This study confirms that mpMRI is a non-invasive technique
able to characterize tumor margin in low-grade PCa.
Tumor characterization and delineation is a crucial step in
focal brachytherapy as only sub-volume of the prostate is
treated with high gradient dose levels. Target volume
margin definition is a hot topic when focal treatments
(e.g. cryotherapy or HIFU) are considered and mpMRI can
bring quantitative answers.
OC-0172 interstitial salvage HDR-brachytherapy for
recurrent prostate cancer after radiation therapy
P. Jiang
1
, C. Van der Horst
2
, B. Kimmig
1
, F. Zinsser
1
, B.
Poppe
3
, U. Luetzen
4
, K.P. Juenemann
5
, F.A. Siebert
1
, J.
Dunst
1
1
UKSH- Campus Kiel, Department of Radiation Oncology,
Kiel, Germany
2
Community Clinic Kiel, Department of Urology-, kiel,
Germany
3
Medical Campus Pius-Hospital- Carl von Ossietzky
University, University Clinic for Medical Radiation
Physics-, Oldenburg, Germany
4
UKSH- Campus Kiel, Department of Nuclear Medicine,
Kiel, Germany
5
UKSH- Campus Kiel, Department of Urology, Kiel,
Germany
Purpose or Objective
There is growing literature on local salvage treatments
following definitive radiation. However, data employing
interstitial high dose rate brachytherapy (HDR-BT) for
salvage treatment are rare, especially those with long-
term outcomes. This is a report of our results as a unique
published cohort with salvage HDR-BT after previous HDR-
BT treatment (Jiang et. al. 2016, brachytherapy, paper in
pressed). Emphasis was put on 5-year outcome and
toxicity.
Material and Methods
From 2009 to 2014, 29 patients with local failure after
previous radiotherapy for prostate cancer were treated
with salvage interstitial HDR-BT. Primary treatment was
combined external beam irradiation (EBRT) with 50Gy plus
HDR-BT-boost with 30 Gy in 27 patients. The primary
treatment carried the total dose to a combined biologic
equivalent dose in 2 Gy per fraction of about 178 Gy, by
assuming an α/β ratio of 1.5 for the tumor and about 146
Gy by an α/β ration of 3. 2 patients had undergone EBRT
with 66.6 Gy of the prostate bed as salvage treatment
after prostatectomy. The interval between primary
treatment and salvage treatment was 5.5 years (mean ±
SD: 5.5 ± 2.8 years).
All 29 patients had biochemical failure according to the
Phoenix definition. The diagnosis of local recurrence was
made on the basis of F-18 labeled cholin-PET. The
presence or co-existence of regional lymph node and/or
distant metastases was excluded by imaging methods.