994 / 1096
S978
ESTRO 36
_______________________________________________________________________________________________
for low risk histology (i.e. G1-2 endometrial
adenocarcinoma) was 100% at 1 and 6 years (p=0.05).
Acute toxicity was registered in 2 (12%) patients: G2
nausea and G2 proctitis in 1 patient (6%), G2 diarrhea, G2
anemia and G2 proctitis in 1(6%) patient. Two patients
(12%) had G1 late rectal bleeding.
Conclusion
Conclusion:
Our data show a good LC particularly in
patients with stage I low risk histology endometrial
cancer. Though number of patients is limited, definitive
HDR-BRT could be an alternative treatment option for
inoperable elderly patients with good compliance and
limited toxicity. Histology is a prognostic factor for LC.
Table 1. Dose schedules
HDR-BRT = high-dose rate brachytherapy
EQD2: Equivalent dose of 2 Gy per fraction calculated
using the equation EQD2 =
([d+ α/β]/[2Gy+α/β]) derived
from linear quadratic model.
Legend: * patients submitted to external beam
radiotherapy and brachytherapy
EP-1780 Postoperative endometrium: 68Gy
EQD2(α/β=3) at 2cc of vagina is related to G2 late
toxicity.
A. Rovirosa
1
, M. Aguilera
2
, C. Ascaso
3
, A. Herreros
4
, J.
Sánchez
5
, J. Garcia-Miguel
6
, S. Sabater
7
, G. Oses
8
, P.
Makiya
9
, S. Cortes
10
, J. Solà
6
, E. Agusti
11
, A. Huguet
6
, A.
Garrido
6
, A. Lloret
6
, C. Baltrons
6
, M. Arenas
12
1
Hospital Clinic Universitari, Radiation Oncology Dpt.,
Barcelona, Spain
2
Hospital Universitario de Caracas, Radiation Oncology
Dpt, Caracas, Venezuela
3
Faculty of Medicine- Universitat de Barcelona, Clinical
Basics Dpt, Barcelona, Spain
4
Hospital Clínic, Radiation Oncology Dpt., Barcelona,
Spain
5
Hospital Clinic Universitari, Finance Dpt, Barcelona,
Spain
6
Hospital Clínic Universitari, Radiation Oncology Dpt,
Barcelona, Spain
7
Hospital General de Alicante, Radaition Oncology Dpt,
Barcelona, Spain
8
Hospital Clínic Universitari, Radiation Oncology,
Barcelona, Spain
9
Hospital Rebagliati, Radiation Oncology Dpt., Lima,
Peru
10
Hospital Clínic Universitari, Radiation Oncolgy,
Barcelona, Spain
11
Hospital Clínic Universitari, Radiation Oncology Dpt,
Barclona, Spain
12
Hospital Sant Joan de Reus, Radiation Oncology Dpt,
Reus, Spain
Purpose or Objective
To evaluate if EQD2
(α/β=3)
at 0.1cc, 1cc and 2cc of vagina in
cylinder vaginal-cuff brachytherapy (VBT) ±external beam
irradiation (EBI) is associated with G2 toxicity in
postoperative endometrial carcinoma (P-EC).
Material and Methods
From June 2014-November 2015,
67 consecutive P-EC
patients received VBT±EBI: 54 EBI (median 45Gy, range 44-
50.4)) +VBT (7Gy) and 13 exclusive BT (6Gy x 3 fractions).
2.5cm of vagina was delineated after CT for 3D treatment
planning. The active source length was 2.5cm. The BT
dose was prescribed at 5mm from the applicator surface.
Patients were treated with HDR
192
Ir source using a
MicroHDR source projector (Nucletron®). D90, V100 and
EQD2
(α/β=3)
at 0.1cc, 1cc and 2cc were calculated.
The mean follow-up was: 23.2 months (range 7.6-46.8).
D90 (cc): median 7.8 (range 4.6-8.9); V100 (Gy): median
7.9 ( range 4.4-10.8).
Vaginal toxicity was prospectively assessed using objective
LENT-SOMA scores. Late vaginal toxicity: 17/67 (25%) 8
with G1 and 9 G2. For this analysis G0 and G1 patients
were considered as no late toxicity (58/67, Group-1) and
9 patients with G2 (9/67,Group-2) were considered as
having late toxicity. Statistics: t-Student test and Chi
squared, alpha=5%.
Results
The median EQD2
(α/β=3)
doses were 88.6Gy (62.8-177.6) for
0.1cc, 72.4Gy (57.1-130.4) for 1cc and 69Gy (53-113.4) for
2cc. There were no differences in toxicity and
EQD2
(α/β=3)
between exclusive VBT vs. EBI+VBT. EQD2
(α/β=3)
:
The mean EQD2
(α/β=3)
:
at 0.1cc was 92.9Gy (SD 17.7) for
Group-1 and 96.3Gy (SD 31.6) for Group-2 (p=0.62); being
72.3Gy (SD 6) at 1cc for Group-1 and 73.5Gy (SD 5.3) for
Group-2 (p= 0.58); and 67.6Gy (SD 6.2) at 2cc for Group-1
and 73.1Gy (SD 10.8) for Group-2 (p=0.03). 20.5% of
patients receiving doses ≥68Gy EQD2
(α/β=3)
at 2cc of vagina
developed G2 toxicity. All patients with G2 toxicity had
received doses ≥68Gy EQD2
(α/β=3)
at 2cc (p=0.04).
Conclusion
68Gy
EQD2
(α/β=3)
doses at 2cc were related to G2 toxicity
in P-EC VBT. In view of these results patients receiving
these doses should be informed of their risk and individual
characteristics should be considered in treatment planning
and follow-up to reduce G2 toxicity. Grant: Spanish
Association Against Cancer (AECC) Foundation
.
EP-1781 statistical and dosimetric analysis of air gaps
in vaginal cuff brachytherapy
S. Abdollahi
1
, L. Rafat-Motavalli
2
, H. Miri-Hakimabad
2
, M.
Mohammadi
1
, E. Hoseinian-Azghadi
2
, N. Mohammadi
2
, N.
Rafat-Motavalli
2
, L. Sobhkhiz-Sabet
1
1
Reza Radiation Oncology Center RROC, medical physics,
Mashad, Iran Islamic Republic of
2
Ferdowsi University of Mashhad, Physics, Mashhad, Iran
Islamic Republic of