697 / 1082
S681
ESTRO 36 2017
_______________________________________________________________________________________________
p
=0,72).
Conclusion
Pathologic response after neoadjuvant therapy for locally
advanced rectal cancer is associated with better
prognostic results. No correlation between immediate or
delayed surgery and tumor regression was observed in this
study, suggesting that tumor response depends on other
factors besides surgical timing. Further studies should be
carried out in order to clearly define predictive factors of
tumour response.
EP-1280 Clinical outcomes of anal squamous cell
carcinoma, treated with IMRT, using UK guidance.
S. Sengupta
1
, S. Padmanaban
2
, C. Jacobs
2
, R. Muirhead
3
1
School of Medicine, University of Oxford, Oxford,
United Kingdom
2
Oxford Cancer Centre, Oxford University Hospitals,
Oxford, United Kingdom
3
CRUK/MRC Oxford Institute for Radiation Oncology,
University of Oxford, Oxford, United Kingdom
Purpose or Objective
The largest phase III trial of radical chemoradiotherapy in
anal cancer to date, the ACT2 study, used a unique
radiotherapy dose, fractionation and target volume to
other studies and series; delivering treatment using 3D
conformal radiotherapy and setting the standard for
treatment delivery in the UK. Following the development
of intensity modulated radiotherapy (IMRT) UK guidance
was produced adapting ACT2 doses and volumes for IMRT
delivery. The acute toxicity of delivery using this guidance
has been published, confirming reduced toxicity with
IMRT; but there is no large series looking at outcome, to
confirm maintained outcomes with this new technique.
We report a single series centre assessing patient
outcomes when utilizing IMRT as per UK guidance.
Material and Methods
Between April 2013 and July 2016, 87 patients with anal
carcinoma were treated with IMRT in the Oxford University
Hospital NHS Trust. We retrospectively reviewed clinical
notes for patients and tumour demographics, rates of
recurrence and colostomy status. Data was collected and
analysed using Microsoft Excel, Microsoft Office
Professional Plus 2013 and IBM SPSS Software Version 23.
Results
The median range of the patient population in this study
was 61 (range 37-90), with 29:71 male:female ratio. Rates
of Tx/T1/T2 and T3/T4 were 62.1% and 37.9%
respectively, node negative (N0) and node positive (N+)
were 48.8% and 51.2% respectively. 96.6% of patients were
free of metastatic disease prior to radiotherapy. The
median follow up time after radiotherapy was 15 months
(range 3 to 38 months).
The 2 year disease free and overall survival was 76.5% and
83.9% respectively. 94% of patients had a 3 month
complete response rate, with 5 patients having an
incomplete response, 4 of whom underwent salvage
surgery.
At the time of analysis, 5 patients had isolated local
relapse following CR at 3 months. Of those, 3 went on to
salvage surgery. 7 patients (8%) had distant disease of
which 3 patients had both local and distant disease.
2 year colostomy free survival was 75.2%. 12 of the
patients had pre-treatment stoma with 7 more patients
requiring a colostomy after radiotherapy.
Conclusion
The outcomes in our series suggest that the excellent
outcomes achieved with 3D conformal radiotherapy in
ACT2 are reproducible with IMRT, delivered according to
UK guidance. A larger multicentre audit of outcomes is
planned to confirm our findings.
EP-1281 Feasibility and Toxicity analysis of dose-
escalation by SIB/VMAT schedule in rectal cancer
patients
A. Re
1
, G. Chiloiro
1
, M.A. Gambacorta
1
, F. Cellini
1
, A.
Pesce
1
, D. Marchesano
1
, G.C. Mattiucci
1
, S. Manfrida
1
, V.
Valentini
1
1
Università Cattolica del Sacro Cuore, Radiation
Oncology Department, Rome, Italy
Purpose or Objective
Evaluation of the feasibility of an intensification of
radiation
dose
by
simultaneous
integrated
boost/Volumetric Modulated Arc Therapy (SIB/VMAT)
technique in patients (pts) affected by Locally Advanced
Rectal Cancer (LARC) based on toxicity profile.
Material and Methods
Pts affected by non-metastatic LARC underwent
neoadjuvant chemo-radiotherapy (CRT). The CRT was
delivered in 25 fractions with SIB-VMAT strategy on two
volumes: Clinical target volume (CTV)2 received a total
dose of 45 Gy/1.8 Gy/fraction on the total mesorectum
and the nodes of drainage; CTV1 received 55
Gy/2.2Gy/fraction as a moderate hypofractionated
schedule on the tumor and the corresponding
mesorectum.
Surgery was planned at least 8 weeks after the end of
CRT. A watch and wait (WW) strategy was considered if
restaging exams showed no detectable disease. Adjuvant
chemotherapy (CT) was considered according to risk
factors. Acute Gastrointestinal (GI), genitourinary (GU)
and hematological (HE) adverse events were recorded
according to CTCAE scale v4.0. Collaterally CRT efficacy
in terms of pathological Complete response (pCR) was
analyzed and Tumor Regression Grade (TRG) on the basis
of Mandard scale was recorded.
Results