ESTRO 36 Abstract Book

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S723 ESTRO 36
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acute GI toxicity grade I was observed in 6 patients (17.1%)
and grade II in 3 patients (8.6%). No late grade III-IV GU or
GI toxicity was detected. For one patient a TURP was
planned at 8 months after treatment, for urethral
stricture.
Only 1 patient (3%) developed biochemical recurrence
after a follow-up of 27 months.
Conclusion
Hypo-RT (63,4 Gy/20 fractions) with a high equivalent BED
(EQD2Gy_tumor = 85 Gy) produces aceptable acute and
sub-acute toxicity rates with excellent outcomes of
biochemical control for intermediate risk prostate cancer.
Longer term follow-up should be analyzed to confirm
these data.
EP-1348 Set-up errors in prostate cancer radiotherapy
based on cone-beam computed tomography.
M. Trignani1, G. Caponigro1, M. Di Biase1, P. Bagalà1, M.D.
Falco1 , A. Vinciguerra1, A. Augurio1, M. Di Tommaso1, L.
Caravatta1, D. Genovesi1
1 Ospedale Clinicizzato S.S. Annunziata, Radiotherapy,
Chieti, Italy
Purpose or Objective
To evaluate set-up accuracy using cone-beam computed
tomography (CBCT) in patients with prostate cancer
receiving VMAT (volumetric modulated arc therapy) or
IMRT (intensity modulated radiation therapy) techniques.
Material and Methods
From January 2015 to September 2016, 1199 CBCT
referred to 98 prostate cancer patients received radiation
treatment at our Institution using Elekta Synergy Agility
Linear Accelerator were acquired, recorded and
evaluated.
All patients underwent to planning computed tomography
(CT) in supine position; knees and ankles were placed in a
steady and comfortable position using a footrest. CT scans
with slices at 5 mm were acquired at 2 mm in condition of
fully bladder (0.75 liter of water, 45 minutes prior to CT
scan) and empty rectum. Planning CT was sent to
Oncentra Master Plan planning system and then via DICOM
to XVI software for co-registration with the CBCT scans.
For the CBCT acquisition we used the “pelvis M15”; the
Grey level algorithm was employed to obtain 3D-3D co-
registration with CT planning. An internal protocol was
adopted to reduce interfraction set-up errors and to
correct systematic errors. This protocol consisted in the
execution of 5 consecutively CBCT during first week of
treatment and once weekly CBCT during RT course. On the
basis of literature data an on-line correction protocol was
adopted: the tolerance level was 3 mm for translation
displacements and 3° for rotations; translation
displacements were applied in case of values >3 mm, while
for rotation >3° patients were repositioned. Then an
offline correction was applied with the mean of first 5
scans used to correct systematic errors with 3 mm. Means
(m) and standard deviations (SD) of all translational (x, y,
z) and rotational displacements were calculated in
relation to the first 5 and the following CBCTs. The
Wilxocon test was used to evaluate statistically significant
differences between displacements related to first 5
CBCTs and to the following CBCTs.
Results
Results are summarized in Table 1. Median values were <3
mm for all CBCTs, for both the first five and following
CBCTs, mean values were within 5mm. Greater shifts were
observed on z axis. Wilcoxon test showed a statistically
significant correlation only for the x (p value = 0.001).
Conclusion
In our study, we have analyzed translational set-up
uncertainties in prostate cancer treatments using CBCT
and we found that all the displacements were within 5
mm, well within the offset established. The action level
of 3 mm currently adopted at our center results safe and
it constitutes a good start point to reduce margin CTV-
PTV.
EP-1349 Adjuvant hypofractionated radiotherapy for
prostate cancer: acute toxicity
S. Saldi1, R. Bellavita2, I. Palumbo3, C. Mariucci1, E.
Arena1, M. Lupattelli2, M. Mendichi1, M. Tenti1, F.
Tamburi2, V. Bini4, C. Aristei3
1University of Perugia, Radiation Oncology Section,
Perugia, Italy
2Perugia General Hospital, Radiation Oncology Section,
Perugia, Italy
3University of Perugia and Perugia General Hospital,
Radiation Oncology Section, Perugia, Italy
4Perugia General Hospital, Internal Medicine Endocrin
and Metabolic Sciences Section, Perugia, Italy
Purpose or Objective
To evaluate acute toxicity and
preliminary outcome of hypofractionated adjuvant
radiotherapy (Hypo-ART) with helical tomotherapy after
radical prostatectomy (RP).
Material and Methods
From February 2014 to July 2016, 30 prostate cancer
patients received Hypo-ART for pT2-3 N0-1 and/or
R1disease. Median age was 67 years (range 53-74). The
surgical Gleason score was: <7 in 8 patients (27%), 7 in 10
(33%) and >7 in 12 (40%). Before RP the median PSA was
7.74 (range: 1.13-44.48) which dropped to 0.025 ng/ml
(range: 0 -0.53) before Hypo-ART. RT schedule: all 30
patients received 2.25 Gy in 29 fractions (total dose: 65.25
Gy) to the prostate/seminal vesicle bed; 15 (50%)
patients also received 1.8 Gy in 29 fractions to the pelvic
lymph nodes (total dose: 52.2 Gy). A simultaneous
integrated boost (SIB) technique was used. Hormone
therapy (LHRH analogue and/or anti-androgen) was
administered to 15 (50%) patients with high risk features.
Toxicity was graded according to the Common
Terminology Criteria for Adverse Events version v4.0.
Biochemical failure was defined by ASTRO criteria. The
Kaplan-Meier method determined time-to-acute toxicity
events. The Mann-Whitney tested compared clinical and
dosimetric variables in groups with and without acute
toxicity.
Results
Median follow-up was 26.5 months (range: 3-31). The
median duration of HT was 21 months (range 4-33). Only
G1-G2 acute genitourinary (GU) and intestinal (GI)
toxicities occurred. Acute grade 1 GU toxicity occurred in
14/30 patients (56%), with 13 (43%) developing cystitis and
1 (3%) hematuria. Acute grade 2 GU toxicity (cystitis)
developed in 3/30 (10%) patients, with 1 also affected by
urinary retension (3%). Acute grade 1 GI toxicity (proctitis)
occurred in 14/30 patients (47%), which was associated
with rectal bleeding in 2 (7%) and diarrhoea in 5 (17%).
Acute grade 2 GI toxicity (proctitis) developed in 3/30
(10%) patients, which was associated with rectal bleeding
in 1 (3%) and diarrhoea in 1 (3%). Post Hypo-ART the
median PSA was 0.01 ng/ml (range:0-0.22) and the nadir
was 0.005 ng/ml (range: 0-0.2). At the last follow-up
no patient presented evidence of biochemical or loco-
regional recurrence. The probability of developing acute
GU on day 44 and GI toxicity on day 43 was 50% (95% CI 41-
46; 95% CI 39-46 respectively ). No differences emerged in
clinical and dosimetric variables in group with or without
acute toxicity.
Conclusion
These results suggest that moderate Hypo -ART is safe,
effective and well-tolerated. A longer follow-up is needed
to assess late toxicity and disease-free survival.