390 / 1082
S375
ESTRO 36 2017
_______________________________________________________________________________________________
Pelvic insufficiency fractures (PIF) are frequently reported
late effect in women who undergo pelvic radiation therapy
(RT) for cervical and uterine carcinomas, ranging from 5-
15%, though the majority of these are asymptomatic.
Other known risk factors include age, pre-existing
osteoporosis, and post-menopausal status. Because the
majority of PIF are clinically insignificant, we sought to
determine predictors of the development of symptomatic
PIF in women undergoing pelvic RT.
Material and Methods
This is a retrospective review of women treated between
1999 and 2013 for uterine or cervical cancer at single
institution. All patients received external beam RT with
either 3DCRT or IMRT technique to at least 45Gy followed
by high dose-rate Intracavitary brachytherapy. Time to
symptomatic PIF was calculated as the time from
completion of RT to diagnostic imaging demonstrating
fracture. Independent t-test and Chi-squared analysis
were utilized to determine association between
demographic and dosimetric variables and symptomatic
PIF.
Results
253 consecutive patients were identified, 77 (30.4%) of
whom had RT plans available for review. The median
patient age at diagnosis was 63. The external beam RT
dose was 45.0-50. The average mean sacral dose was
37.8Gy (range: 27-44.7Gy). Seven patients (9.1%) were
diagnosed with symptomatic PIF at a median time from RT
of 23.6 months (range: 7-98 months). Median sacral V20
and V30 were 99.7% and 83.7%, respectively. Sacral V20
was significantly associated with symptomatic PIF (p=.008)
and V30 trended towards significance (p=.054). Sacral V30
≥ 83.7% predicted for the risk of symptomatic PIF (p=.05).
Conclusion
This is the first study to correlate symptomatic pelvic
insufficiency fracture to dosimetric parameters involved
in pelvic RT in women. Limiting sacral V30 < 83.7% is
recommended and further study is warranted. We will
further validate this data in our larger dataset given the
small number of events.
Poster: Clinical track: Prostate
PO-0723 Phase II study with FFF linac-based SBRT in 5
fractions for localized prostate cancer
F. Alongi
1
, U. Tebano
1
, S. Fersino
1
, A. Fiorentino
1
, R.
Mazzola
1
, N. Giaj-Levra
1
, F. Ricchetti
1
, D. Aiello
1
, G.
Sicignano
1
, S. Naccarato
1
, R. Ruggieri
1
1
Sacro Cuore Don Calabria Cancer Care Center, Division
of Radiation Oncology, Negrar, Italy
Purpose or Objective
SBRT is recently considered a potential treatment option
in selected prostate cancer (PC) patients. Usually,
prostate SBRT has been delivered every other day in order
to favour normal tissues recovery, minimizing side effects.
Flattening Filter Free (FFF) delivery is a treatment
modality able to reduce treatment beam-on time,
decreasing patient positioning uncertainties. Aim of the
present phase-II study is to evaluate the feasibility, side
effects and biochemical control of FFF SBRT delivered in
5 consecutive days in a cohort of localized PC patients.
Material and Methods
The study, approved by Ethical Committee, started on
January 2014. Inclusion criteria were: age ≤ 80 years,
World Health Organization performance status ≤ 2,
histologically proven prostate adenocarcinoma, low-
intermediate risk according to D'Amico criteria, no distant
metastases, no previous surgery other than TURP, no other
malignant tumor in the previous 5 years, a pre-SBRT
International Prostatic Symptoms Score (IPSS) ranged
between 0 and 7.
The SBRT-schedule was 35Gy for low risk and 37.5Gy for
intermediate risk PC in 5 fractions, delivered in 5
consecutive days. SBRT was delivered with volumetric
modulated radiation therapy (VMAT). Toxicity assessment
was performed according to CTCAE v4.0 scale.
Neoadjuvant/concomitant
hormonal-therapy
was
prescribed according to risk classification.
Results
At the time of the analysis,
forty-two patients were
recruited in the protocol and treated. Median age was 74
years (63-80), Median follow-up was 19 months (range: 12-
31). According to risk-category, 31/42 patients were low-
risk and 11/42 were intermediate risk. Median initial PSA
was 6.1 ng/ml (range, 3.4-12.8 ng/ml). Median Gleason
score was 6 (6-7). IPSS pre-SBRT was registered for all
patients, with a median value of 4 (range, 0 - 10). All
patients completed the treatment as planned. Acute
genitourinary toxicity was: G0 29/42 (70%), G1 7/42 (17%),
G2 6/42 (13%). Acute gastrointestinal toxicity was: G0
36/42 (86%), G1 4/42 (9%), G2 2/42 (5%). No acute
toxicities > G3 were recorded. At the time of the analysis
late GU and GI toxicities were: GU-G0 33/42 (78%), GU-G1
7/42 (17%), GU-G2 1/42 (2%), GU-G3 1/42 (2%); GI-G0
39/42 (93%), GI-G1 3/42 (7%) and the median value of IPSS
was 4.5 (range, 0 - 20). To date, biochemical control was
100%.
Conclusion
The present
FFF SBRT phase-II study for low-intermediate
PC delivered in 5 consecutive days showed to be feasible
and well tolerated as well as other series with the same
technique and fractionation delivered every other day
(Alongi et al Radiation Oncology 2013). Longer follow-up
is needed to assess late toxicity profile and clinical
outcomes.
PO-0724 Moderate hypofractionated radiotherapy in
prostate cancer: a meta-analysis from randomized trials
Z. Yin
1
, Z. Yuan
2
, J. You
2
1
Tianjin Medical University Cancer Institute & Hospital,
Radiotherapy, tianjin, China
2
Tianjin Medical University Cancer Institute and
Hospital, Department of radiotherapy, Tianjin, China
Purpose or Objective
Conventional radiotherapy (C-RT) with dose more than
75.6Gy was the current standard treatment for patients
with localized prostate cancer. While prostate cancer’s
biological characteristics, lowα/βratio, makes it more
radiosensitive to hypo-fractionation. To compare the
efficacy and late toxicity of moderate (2.5-3.4Gy) hypo-
fractionated radiotherapy (H-RT) in localized prostate
cancer with conventional fractionated RT (C-RT), we
performed a systematic review and meta-analysis of
published randomized trials.
Material and Methods
Systematic search on published RCTs in English according
to Cochrane review guidelines in database of Pubmed,
Embase, Cochrane, web of science, and Wiley Online
Library were carried out. Outcome of interest was
biochemical or clinical disease failure (BCDF), biochemical
failure (BF), overall survival (OS) and late toxicities
Results
6 of 341 studies fulfilled inclusions with 6931 patients.
There was no significant difference in BCDF between H-RT
and C-RT (RR=0.94, 95% CI: 0.83-1.06,
p
=0.31), with a
moderate heterogeneity (Chi
2
=6.23; df= 4[P=0.18];
I
2
=36%). We grouped them into dose-escalated H-RT and
no dose-escalated H-RT, dose-escalated H-RT significantly
improved BCDF compared with C-RT (RR=0.86, 95%CI:
0.74-0.99,
p
=0.04). Patients who received H-RT showed a
lower BF (RR=0.78, 95% CI: 0.63-0.97,
p
=0.03), without
heterogeneity (Chi
2
=0.86; df=2[P=0.65];
I
2
=0%). There was
no significant difference in overall survival (RR=0.89, 95%
CI: 0.76-1.03,
p
=0.12) between H-RT and C-RT, also no
heterogeneity noted (Chi
2
=3.53; df=4[P=0.47];
I
2
=0%). As