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S315
ESTRO 36 2017
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The study population consisted of 931 previously
untreated, biopsy-proven, and no distant metastasis NPC
patients who finished curative radiotherapy with/without
chemotherapy at our department. The pre-treatment
pEBV DNA level was measured by the real-time
quantitative polymerase chain reaction. We analyzed the
relationship between the pEBV DNA status and clinical
characteristics. Various survival curves were compared
between the patients with detectable and undetectable
pEBV DNA by the Kaplan-Meier method.
Results
EBV DNA signal (> 0 copies/mL) was detected in 90.8%
(845/931) NPC patients’ plasma before treatment. The
percentages in patents with undetectable EBV DNA were
inversely associated with presenting stages (24.6% for
stage I/II, 8.5% for stage III and 2.8% for stage IV, P<0.001).
The pEBV DNA levels were positively correlated with
clinical stage (P<0.001). The age, gender, and
pathological type between the patients with detectable
and undetectable pre-treatment pEBV DNA were similar.
However, patients with detectable pre-treatment pEBV
DNA had relatively poor performance status, advanced T-
classification, advanced N-classification, and advanced
overall stage than those with undetectable pEBV DNA. The
overall survival (HR=0.4413, 95% CI = 0.29-0.67, P=0.0004,
10-year rate = 62.2% vs. 90.3%), neck failure-free survival
(HR=0.3285, 95% CI = 0.12-0.93, P=0.0397, 10-year rate =
94.4% vs. 100%), and distant metastasis-free survival
(HR=0.3751, 95% CI = 0.23-0.62, P=0.0002, 10-year rate =
79.9% vs. 97.7%) were significantly lower in patients with
detectable pEBV DNA than in those with undetectable
pEBV DNA. The local failure-free survival was similar
between both subgroups (HR=0.8740, 95% CI = 0.46-1.67,
P=0.9362, 10-year rate = 85.6% vs. 89.2%).
Conclusion
NPC patients presented with detectable pEBV DNA before
treatment were associated with higher clinical stages and
significant worse survivals.
PO-0612 Significance of co-expression of mutant p53
protein and Ki67 in locally advanced HNSCC post chemo-
RT
P. Baskaran Shanmuga
1
, K. Periasamy
1
, S. Sharma
2
, G.K.
Singh
1
, V. Yadav
1
, A. Gupta
1
, J. Kaur
1
, A.K. Mandal
2
, K.T.
Bhowmik
1
1
Safdarjung Hospital, Radiotherapy, New Delhi, India
2
Safdarjung Hospital, Pathology, New Delhi, India
Purpose or Objective
To know the significance of the co-expression of mutant
p53 protein and Ki67 in locally advanced HNSCC with
respect to response to chemoradiation (CRT) and
locoregional failure (LRF), distant metastasis (DM) and
overall survival (OS) at 1 year.
Material and Methods
This prospective observational study included 62 patients
with stage III-IV non nasopharyngeal HNSCC of which 58
patients completed CRT. Immunohistochemistry was done
on the pre-treatment biopsy specimens and the expression
of p53 and Ki67 in the tumor were graded based on the
degree of nuclear staining. During statistical analysis,
patients having co-expression (p53+/Ki67+) were
categorised in one group and the rest in the non-co-
expressed group (p53-/Ki67-, p53+/Ki67-, p53-/Ki67+).
The patients were followed up for a minimum period of 1
year and the association between the co-expression of the
markers and the tumor response to CRT and LRF, DM and
OS at 1 year were analysed.
Results
57% (33) patients showed co-expression of mutant p53 and
Ki67 while 43% (25) patients fell in the non-co-expressed
group. There was a statistically significant association
between the co-expression of the markers and the
parameters such as age <50 years, N2 stage, TNM stage IVA
and partial response(PR) to CRT at 8 weeks. Similarly, at
1 year, the absence of co-expression was associated
significantly with the locoregional control of the disease
while the presence was associated with LRF.
Even though 8/9 patients with DM showed co-expression,
a statistically significant association was not reached on
analysis (p-value 0.064). The relative risk of PR and LRF
were 4.16 and 3.59 respectively with p53 and Ki67 co-
expression.
On multivariate analysis, the co-expression of the markers
was found to be a statistically significant independent
predicting factor for PR at 8 weeks post CRT and LRF at 1
year with odds ratio 10.50 and 7.12 respectively, however,
the N2 stage was a statistically significant independent
factor of DM and mortality at 1 year with odds ratio of 6.16
and 11.14 respectively.
Conclusion
These results signify that the co-expression of mutant p53
and Ki67 has specific role in the clinical course of locally
advanced HNSCC, significant in predicting PR response to
CRT and LRF at 1 year. Advanced Nodal stage (N2) has
emerged as an independent predictor for DM and mortality
at 1 year.
PO-0613 Effect of geometric GTV-CTV margins in
national contouring guidelines
C.R. Hansen
1,2
, J. Johansen
3
, E. Samsøe
4
, E. Andersen
5
,
J.B. Petersen
6
, K. Jensen
7
, H.M.B. Sand
8
, L.J. Andersen
8
,
C. Grau
7
1
Odense University Hospital, Laboratory of Radiation
Physics, Odense, Denmark
2
University of Southern Denmark, Faculty of Health
Sciences, Odense, Denmark
3
Odense University Hospital, Department of Oncology,
Odense, Denmark
4
University Hospital Herlev, Radiotherapy Research Unit-
Department of Oncology, Herlev, Denmark
5
University Hospital Herlev, Department of Oncology,
Herlev, Denmark
6
Aarhus University Hospital, Department of Medical
Physics, Aarhus, Denmark
7
Aarhus University Hospital, Department of Oncology,
Aarhus, Denmark
8
Aalborg Hospital, Department of Oncology, Aalborg,
Denmark