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ESTRO 36 2017
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about the response of the OARs to the radiation, and
should be prospectively evaluated.
EP-1217 Non-small cell lung cancer invading the
vertebra: what is the optimal strategy for radiation?
S. Appel
1
, J. Goldstein
1
, Z. Symon
1
, Y. Lawrence
1
, M. Ben
aiun
1
, N. Honig
1
, T. Rabin
1
1
Chaim Sheba Medical Center, Radiation Oncology,
Ramat Gan, Israel
Purpose or Objective
Non-small cell lung cancer that invades the vertebra (T4)
may cause significant morbidities if uncontrolled locally
with limited options for salvage re-irradiation. The spinal
foramina and vertebral body are sites of potential tumor
invasion and sparing them may compromise local tumor
control probabilities. In our institution, we incorporated
the strategy of including the entire vertebra and the spinal
canal to the allowed dose in two strategies: shrinking
fields and integrated boost.
We hypothesized that treating with integrated boost
including the spine canal and the vertebral body will result
in higher tumor BED than treatment with shrinking fields
with off spine boost.
Material and Methods
we retrospectively reviewed 14 cases that were T4 and
treated with radiation therapy in our institute and
included the spine and vertebra, during the years 2013-
2016. We searched the radiation plans for mean dose to
GTV, spine and fraction size. We calculated the
biologically effective doses (BED) per the linear quadratic
model, for the GTV using α/β=10 and for the spine using
α/β=3. In the shrinking fields two calculations were
performed for each step, to account for the different
doses to the spine.
Results
•
Shrinking field:
( 4 patients) median prescription dose was
59 Gy (55-66 Gy) in 2 Gy per fraction in 29 (26-33) fractions
Median GTV dose was 61.3 Gy (57-68.7Gy). The maximal
dose to spine with the composite planes, including the exit
dose from the boost plan was median of 50.6 Gy (48.4-53.5
Gy). Median BED to PTV was 71Gy (68.1-79.2Gy) GTV was
74.3 Gy (66.6-83 Gy) and to the spine was 82.2 Gy (75.3-
86.4 Gy)
•
Integrated boost
: ( 10 patients) median prescription dose
was 61.6 Gy (54-66 Gy) in 2.21 Gy per fraction (1.96-2.28
Gy) in 28 (28-33) fractions. The median GTV dose was 62.6
Gy (55-64.7 Gy). The median maximal dose to the spine
was 50 Gy (47.8-52.7Gy), in 1.8 Gy per fraction (1.6-1.9
Gy). Median BED to PTV was 75.2 Gy (64.8-79.2 Gy) GTV
was 76.4 Gy (66.6-78.5 Gy), and the median BED to the
spine 79.2 Gy (75-85.9 Gy).
1.
example of integrated boost treatment color wash. the
GTV is bold red and is recieving mean dose of 63 Gy .. the
outer red delineates the elective dose and includes the
spinal canal and the adjacent vertebra.higher dose is
manipulated inside the GTV, to allow higher BED while
elective dose is prescrived to the high risk elective area.
)
2.
Table 1: Comparison between treatment strategies:
Shrinking fields vs. Integrated boost: Doses prescribed to
the PTV, actual doses to the GTV and maximal doses to
the spine, and the calculated doses to the GTV and the
spine according to the linear quadratic model.
Conclusion
Integrated boost strategy resulted in modestly higher BED
to the PTV and GTV than shrinking fields, and lower BED
to the spine. Thus, the integrated boost strategy should
be preferred.
EP-1218 Prognostic Values of Tumor Markers in Lung
Cancer Patients Treated with Definitive
Chemoradiotherapy
J.H. Chung
1
, J.S. Kim
1
1
Seoul National University Bundang Hospital, Department
of Radiation Oncology, Seongnam-si, Korea Republic of
Purpose or Objective
Prognostic value of serum carcinoembryonic antigen
(CEA), squamous cell carcinoma antigen (SCC),
cytokeratin 19 fragment antigen 21-1 (Cyfra 21-1) and
neuron specific enolase (NSE) has been investigated in
patients with early or advanced lung cancer. However, the
role of these markers in patients undergoing concurrent
chemoradiotherapy (CCRT) for inoperable lung cancer is
unclear.
Material and Methods
In this retrospective study, 179 patients (154 men and 25
women; mean age, 62.2±9.7 years) with inoperable lung
cancer underwent definitive CCRT at our institution from
2003 to 2014. Histologic classification was as follows:
adenocarcinoma 37 (21%), squamous cell carcinoma 62
(35%), other non-small cell lung cancer (NSCLC) 6 (3%),
and small cell carcinoma 74 (41%). Age, gender, histology,
tumor diameter, clinical N stage, and pre- and post-CCRT
serum CEA, SCC, Cyfra 21-1, and NSE levels were chosen
as study variables.