ESTRO 36 Abstract Book

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S640 ESTRO 36
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Material and Methods
From 2006 to 2010, 832 patients with early-stated breast
cancer treated by conservative surgery underwent 3D-
conformal whole breast RT in the lateral decubitus
position at Institut Curie. All types of cup size was
included. The acute toxicity of treatement was evaluated
weekly using NCI CTC v3.0 scale, and the late toxicity was
evaluated once a year and started one year after the end
of RT. A dosimetric study was performed to analyse the
mean cardiac dose and the mean homolateral and
controlateral lung doses.
Results
median of follow up is 6.4 years, median age is 61,5 years
(min29-max90), and median body mass index is 26.3. 51%
have left breast cancer and 49% have right breast cancer.
Different type of fraction/dose were performed : 46.5%
66Gy in 33 fractions, 17.9% 50Gy in 25 fractions, 26.1% 40
or 41.6Gy in 15 or 13 fractions and 30Gy in 5 fractions.
Acute epidermitis was present in 93% with a median of
apparition of 4 weeks, and only 2,8% grade 3. In
multivariate analysis, the cup size has signicative
influence (p=0,0004) and the fractionation has a
significative influence (p=0,0001). After one year 94.1%
had no epidermitis. No cardiac or pulmonary toxicity was
reported. For normofractionation (2Gy fractions, 50 Gy on
the whole breast and 16Gy boost on the tumor bed) : Mean
dose to homolatéral lung (HL) is 1,4 Gy (min 0,63 Gy-max
3 Gy), mean dose to controlateral lung (CL) is 0,07Gy
(min0,37Gy-max1Gy) mean cardiac dose is 1,14 Gy
(min0,54 Gy – max4 Gy). In hypofractionation : for 41,6Gy
in 13 fractions schedule : mean dose to HL is 0,87Gy
(min0,38 Gy-max5 Gy), mean dose to CL is 0,03 Gy (min0,3
Gy-max3 Gy) mean cardiac dose is 0,77 Gy (min0,38 Gy-
max9 Gy). For 40 Gy en 15 fractions schedule : mean dose
to HL is 0,96 Gy (min0,38 Gy-max4 Gy), mean dose to CL
is 0,04 Gy (min0,02 Gy-max2,28 Gy) mean cardiac dose is
0,74Gy (min0,3 Gy-max1 Gy). In the 28,5Gy en 5 fractions
schedule : Mean dose to HL is 0,53Gy (min0,26Gy-
max3Gy), mean dose to CL is 0Gy (min0 Gy-max0,4 Gy)
mean cardiac dose is 0,37Gy (min0,6 Gy-max5 Gy). Median
overall survival is not reached, there is no influence of
fractionation on overall survival. Relapse-free survival is
not reached, with only 36 relapses without influence of
fractionation.
Conclusion
whole breast radiotherapy in the lateral decubitus position
provides excellent results with very low mean cardiac dose
and mean pulmonary dose. There is no cardiac or
pulmonary toxicity in this study. And it’s also very well
tolerated with very good acute toxicity profile.
EP-1181 dose to non-routinely delineated risk organs in
post left conservative surgery conformal breast RT
M. Abdelwahed1, M.A.H. Mohamed Abdelrahman Hassan 2
1 As-Salam International Hospital, oncology, Cairo, Egypt
2 Kasr Alaini Center of Clinical Oncology & Nuclear
Medicine NEMROCK, clinicla oncology, cairo, Egypt
Purpose or Objective
This is a dosimetric study aiming at evaluation of radiation
doses to risk organs particularly (brachial plexus, coronary
artery & thyroid gland) in previously treated breast cancer
cases at Kasr Alaini Center of Clinical Oncology & Nuclear
Medicine after left Breast Conservative Surgery (BCS)
Our aim was to identify the patients' subgroups in need for
routine delineation of these risk organs to avoid toxic
doses to them.
Material and Methods
Twenty five female patients with left BCS treated with
external beam radiotherapy to the left breast and
supraclavicular region. Delineation of the coronaries was
done according to the University of Michigan Medical
Center; while the brachial plexus was delineated
according to the RTOG guidelines. Patient measures like
body mass index (BMI), mid beam cut separation, Central
lung distance, Maximum heart distance (MHD) and doses
to risk organs were documented (Heart V30 & heart Dmean,
brachial plexus Dmax , thyroid gland D mean,…)
Results
Age of the patients ranged from 35years to 70 years
(median=54years). BMI ranged from 22.1 to 47.6
(mean=34.2±6.7). MHD mean value was 2.9±1.1cm while
the heart V 30 mean value was 3.44±3.59% with heart D mean
range from 1.2 up to 9.00Gy (mean=3.92±2.02Gy). The
anterior descending coronary artery (ADCA) Dmax was
41.9±6.60Gy while the ADCA Dmean was 23.4±10.9Gy.
ADCA Dmean increased from 18.5±10.9Gy with MHD ≤3cm to
27.9±9.1Gy with MHD >3cm (ρ-value 0.030). ADCA Dmean
was also related to V30 of the heart as the ADCA Dmean
was 16.9±10.5Gy with V30 <2% while ADCA Dmean was
29.5±7.3Gy with V30 ≥2% (ρ-value=0.005).
BMI showed borderline significance on ADCA Dmax when the
BMI was <30, the ADCA Dmax was 37.3±10.0Gy while it was
43.7±43.7Gy when BMI ≥30 with a ρ-value 0.074.
None of the outcome parameters had clinical significance
related to the thyroid gland or brachial plexus, The
brachial plexus Dmax was 46.7±3.0Gy with median value
46.0Gy while the thyroid gland Dmean was 20.6±5.3Gy with
median value 20.0Gy.
Conclusion
A significant dose may be received to non-routinely
delineated organs at risk (brachial plexus, coronary artery
& thyroid gland) in post-operative loco-regional
radiotherapy of patients with left breast cancer after BCS.
A significantly higher dose was received to left ADCA in
cases with high MHD & heart V30 while borderline
significance on ADCA in obese patients where obesity is a
known risk factor for developing coronary artery diseases.
EP-1182 Locoregional treatment of breast cancer with
IMRT: a single center experience
I. Ratosa1, A. Jenko2, R. Hudej2, F. Kos2, A. Gojkovic
Horvat 1, D. Golo 1, T. Marinko1, M.S. Paulin Kosir1, J.
Gugic1
1Institute of Oncology Ljubljana, Department of
Radiation Oncology, Ljubljana, Slovenia
2Institute of Oncology Ljubljana, Department of
Radiation Oncology- Section of Medical Physics,
Ljubljana, Slovenia
Purpose or Objective
To evaluate implementation of breast/chest wall and
locoregional lymph nodes irradiation with inverse-planned
IMRT in patients with challenging anatomy.
Material and Methods
Since 2014, 13 patients with challenging anatomy (8 left-,
5 right-sided) were treated with locoregional IMRT on
institutional protocol because standard mono-isocentric
3D-CRT was insufficient in sparing organs at risk (OARs).
Dose prescription to planning target volume (PTV) was 50
Gy in 25 daily fractions; 3 patients were also prescribed
boost dose 10−16 Gy. Treatment planning was done on
Elekta Monaco TPS with Monte Carlo calculation
algorithm. In the IMRT plan 9 beams with the energy of 6
MV were positioned so that the first two beams were
placed tangentially on the PTV (as in a 3D-CRT plan) and
the rest were redistributed equidistantly between the
tangential pair. The cranial part of beams that would pass
through the shoulder into the PTV was blocked with jaws.
Two segmetation methods were used, Step-and-Shoot for
the first 7 patients and Dynamic MLC (dMLC) for the rest.
The primary endpoint in treatment planning was CTV
coverage. Radiation was delivered on Elekta Synergy™
Platform linac for Step-and-Shoot mode and Elekta Versa
HD™ for dMLC mode.