Download FIDUCIAL MARKERS FOR ADAPTIVE IGRT IN LOCALIZED

FIDUCIAL MARKERS FOR ADAPTIVE IGRT IN LOCALIZED PROSTATE
CANCER: 7 YEARS SINGLE CENTRE EXPERIENCE
1
V. Lacetera, 2 M. Cardinali, 2 G. Mantello, 2 F. Fenu, 1 G. Sbrollini, 1A. Conti,
Maggi, 1 G. Muzzonigro, 4 A.B. Galosi
3
S.
1
Clinica Urologica, 2 SOD Radioterapia, 3 SOD Fisica Sanitaria,Azienda-OspedalieroUniversitaria Ospedali Riuniti Ancona. 4 UOC di Urologia di Fermo
BACKGROUND AND AIM: The prostate gland can be displaced by more than 1
cm on day-to-day radiotherapy session resulting in geographical miss of the target
and unintentional irradiation of surrounding critical structures. For this reason, a
standard margin of 1 cm (CTV-PTV margin) is added to CTV to define the PTV.
Image-Guided Radiotherapy (IGRT) allows the inter-fraction prostate motion
correction. Moreover, gold markers inserted in the prostate gland can help the
visualization and correction of prostate position before treatment. The aim of our
study is to describe our technique of ultrasound-guided implantation of gold markers
in the prostate for adaptive IGRT to obtain a better 3-D visibility of the prostate in a
group of low-intermediate prostate cancer (PCA) patients and to report the main
advantages in terms of reduction of CTV-PTV margins and consequently of side
effects.
MATERIALS AND METHODS: 78 low risk cT1-2 prostate confined PCA patients,
median age 75 y (60-81) were submitted to intra-prostatic implantation of gold
marker for adaptive IGRT between January 2007 and march 2014. Inclusion criteria:
low-intermediate risk prostate cancer patients according to D’Amico classification
(PSA <10, cT<3 using as staging tools DRE-TRUS-endocoil-MRI, Gleason Score <8).
Gold markers were inserted on ultrasound guidance by the 2 referring Urologist (AG,
VL) using a GE logic-Q P5 machine with end-fire probe (6-8 MHz). We recorded
early and late complications of the procedure instructing patients to contact the
radiation oncologist if there were any problems during the week after implantation.
The Planning CT (CTsim) was acquired (1mm) 7 days after implantation, when
markers stability was achieved. In the first 54 patients the CTV was delineated as the
prostate only and a standard margin (10 mm) was added to define the PTV. A daily
markers match between CBCT and CTsim was performed during the whole
treatment, in order to correct inter-fraction prostate motion. For each patient, the first
five CBCTs were then used to create a patient personalized PTV (re PTV) obtained
as a merged volume including the 5 days CTV position. With the aim to calculate the
gain of using gold markers, the maximum distance between the CTV and the re PTV,
for each direction, was assessed for each patient. The median value of the measured
distances, among the whole population, per each direction, was indeed used to define
an anisotropic margin and to compare it with the standard ones. All the patients were
submitted an active follow up. The late toxicity was recorded and classified according
to the LENT SOMA score
RESULTS: Description of Technique: prior to fiducial marker implantation, all
patients were given an information consent describing the risks of the procedure and
the rationale for undergoing fiducial marker implantation. Patients had an enema the
morning of the procedure and were placed on antibiotics (fluorchinolonic) from the
day before to 4 days after procedure. Patients were instructed to stop anticoagulant
and antiplatelet medications 7–10 days before the implant if appropriate. With the
patient in left lateral position we used an intrarectal instillation of lidocaine-prilocain
cream and a 5 ml povidone-iodium enema 5 minuts before insertion of the probe; a
local nerve block by injecting lidocaine 1% at the angle between the seminal vesicle
and prostate on either side immediate prior to insertion of the fiducials. Three fiducial
gold markers (0.9 mm x 3 mm) were placed in the prostate (lateral mid left gland,
apex and right base) under ultrasound guidance. The correct gold markers position
was verified by fluoroscopy in all the cases. No cases of severe early or late
complications are reported (bleeding, infections): the commonest new symptom
following the procedure was urinary frequency affecting 10% of patients. Haematuria,
rectal bleeding, dysuria and haematospermia affected 5–15% of patients, all cases at
Grade 1 or 2. Mean pain score during the procedure was 2 (range 0–10).
IGRT implication and side effects: The re-PTVs resulted thinner than standard ones
(10 mm) for all the patients: 1 mm cranial, 1 mm caudal, 3.5 mm anterior, 3 mm
posterior, 2 mm left and 2.5 mm right. The toxicity was reported for 57/78 patients
with at least 12 months follow up. At a median follow up of 34 months (12-84) we
recorded 8 G1, 5 G2 late rectal toxicity and 8 G1, 1 G2, 2 G3 late bladder toxicity.
26/57 patients referred sexual impotence, mainly as worsening of pre-radiotherapy
impotence due to hormonal therapy.
CONCLUSIONS: We report our technique of ultrasound-guided fiducial gold
markers implantation with its early and late complications in a group of PCA patients:
it’s a safe and well-tollerated procedure and it results helpful to reduce CTV-PTV
margin in all cases. As expected, toxicity resulted were very low, with few cases of
G1-G2 late side effects and only 2 cases of G3 bladder toxicity.