ESTRO 36 Abstract Book

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S87 ESTRO 36 2017
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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 Horst2, B. Kimmig1, F. Zinsser1, B.
Poppe 3, U. Luetzen4, K.P. Juenemann5, F.A. Siebert1, J.
Dunst1
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.
Salvage HDR-BT was given in 3 fractions with weekly
intervals. The target volume covered the peripheral zone
of the prostate and the PET-positive area and was treated
with 10 Gy per fraction. The isodose coverage of the
treatment in clinical practice followed this priority: the
peripheral zone> rectum> urethra> the whole gland. The
biologic equivalent dose of the salvage brachytherapy in 2
Gy per fraction was 98 Gy by assuming an α/β ratio of 1.5
and 78 Gy by a α/β ratio of 3.
Overall survival (OS) and biochemical failure were
calculated after the salvage brachytherapy using the
Kaplan- Meier method. Acute and late genitourinary and
gastrointestinal toxicities were documented according to
common terminology criteria for adverse events (CTCAE v
4.0).
Results
22 patients had a minimum follow-up of 60 months after
salvage treatment. 3 patients died after salvage
treatment; causes of death were malignant melanoma,
multiple organ failure and pneumonia. The 5-year OS was
95.5% with a disease-specific survival of 100% after 5
years. The 5-year biochemical control was 45%. Late grade
2 gastrointestinal toxicities were observed in 2 patients
(9%). No grade 3 or higher gastrointestinal late toxicities
were observed. Urinary incontinence was found in 2
patients (9%) and grade 2 obstruction of urinary tract
occurred in 1 patient (4%).
Conclusion
Interstitial HDR brachyther apy was feasible and effective
in the treatment of locally recurrent prostate cancer after
definitive radiotherapy. The long-term toxicity was low
and acceptable.
OC-0173 Low incidence of severe toxicity by focal sa
lvage HDR brachytherapy in prostate cancer
recurrences
M. Maenhout 1, M. Van Vulpen1, M.A. Moerland1, M.
Peters1, M.A.A. Van den Bosch2, J.R.N. Van der Voort van
Zyp1
1UMC Utrecht, Department of Radiation Oncology,
Utrecht, The Netherlands
2UMC Utrecht, Department of Radiology, Utrecht, The
Netherlands
Purpose or Objective
Whole gland salvage treatment for locally recurrent
prostate cancer after primary radiotherapy has a high rate
of severe toxicity. The standard of care in case of a local
recurrence is androgen deprivation therapy (ADT), which
has significant side-effects and influence on quality of life.
Focal salvage treatment might lead to acceptable toxicity
and concurrently postpone or even avoid the use of ADT.
Here, acute toxicity and preliminary biochemical
outcomes are described after MRI-guided focal salvage
high dose rate (HDR) brachytherapy in patients with
radiorecurrent prostate cancer.
Material and Methods
17 patients with a pathology proven local recurrence have
been treated with an outpatient single fraction of 19Gy
focal HDR brachytherapy in a suite equipped with a 1.5
Tesla MRI scanner for treatment guidance. Primary
radiotherapy consisted of external beam radiotherapy or
brachytherapy. Gross tumor volume (GTV) delineation was
performed using Ga-68-PSMA or F18-Choline PET together
with multiparametric 3.0Tesla MRI in all patients. A
margin inside the prostate of 5 mm was added to define
clinical target volume (CTV) and no margin for planning
target volume (PTV) was added. Catheters were inserted
under ultrasound guidance and definitive treatment
planning was based on the actual MRI based catheter
positions and delineations. All patients had a PSA at time
of recurrence of <10ng/mL and a PSA- doubling time of ≥1
year. Toxicity was measured using the CTCAE version 4.
Results