ESTRO 36 Abstract Book

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S264 ESTRO 36 2017
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current TNM for NPC, failure patterns, and outcomes were
compared between OPC and NPC.
Results
A total of 802 HPV+ OPC and 369 NPC (360 EBER+ and 9
HPV+) were eligible. Compared to NPC, OPC were older
(median age: 59 vs 52), and comprised more males (83% vs
67%), Caucasians (94% vs 20%; Asian 4% vs 75%), smokers
(66% vs 40%), and drinkers (35% vs 9%) (all p<0.01). OPC
presented more often as T1-T2 (58% vs 43%), and/or
unilateral neck diseases (57% vs 24%) (all p<0.01). Median
follow up was 4.5 years for OPC and 6.1 years for NPC.
Distant metastasis (DM) was the main form of failure for
both diseases and occurred in 92 (11%) OPC and 51 (14%)
NPC patients. Most DM (85% OPC and 76% NPC) did not have
local or regional failures (p=0.22). DM to multiple sites was
common for both (51% OPC DM and 35% NPC DM) and most
commonly to lung, liver, and bone for both. However, DM
to brain was more often in OPC vs NPC (13% vs 2%, p=0.03).
Compared to NPC, OPC had slightly higher 5-year
recurrence-free survival (RFS) (84% vs 79%, p=0.01) but
became non-significant after adjusting for TNM (HR 0.89,
p=0.40). RFS for OPC was higher in T1 (93% vs 88%,
p=0.045) or N0 (91% vs 78%, p=0.047), but similar for T2
(88% vs 80%, p=0.13), T3 (80% vs 81%, p=0.76), T4 (68% vs
62%, p=0.61), N1 (88% vs 82%, p=0.09), N2 (77% vs 81%,
p=0.66), and N3 (67% vs 60%, p=0.75) diseases. Similar RFS
was found for the HPV+ OPC specific TNM (ICON-S) stage I
and current NPC I-II [both T1-2N0-1] (91% vs 90%, p=0.26),
OPC ICON-S II vs NPC III [both T1-2N2 or T3N0-2] (84% vs
87%, p=0.95), and OPC ICON-S III vs NPC IVA-B [both T4 or
N3] (69% vs 63%, p=0.56). Long-term survivors (survived >2
years after DM) were found in 24/92 (26%) OPC and 15/51
(29%) NPC with DM. Overall survival after DM for OPC and
NPC were also similar (5-year: 17% vs 22%, p=0.20).
Conclusion
This large western cohort study depicted remarkable
similarity with few differences in clinical presentation and
outcomes between viral related OPC and NPC in the IMRT
era. Patterns of relapse and oncologic outcomes are very
similar by TNM classification. DM is the main form of
failure and long-term survivors after DM are seen for both
diseases. Such similarities in clinical behavior could
reflect common mechanisms of oncogenesis, metastasis,
and radio-/chemo- sensitivity and/or resistance induced
by HPV and EBV. Uncovering these pathways could present
new therapeutic opportunities for both diseases in the
future.
PV-0507 NGS for prognostic stratification in oral
cancer harboring lymph node without extracapsular
spread
H.M. Wang1, C.T. Liao2 , T.C. Yen3, S.J. Chen4, L.Y. Lee5,
C.H. Hsieh1, C.Y. Lin6, S.H. Ng7
1 Chang Gung Memorial Hospital, Division of medical
oncology- Department of internal medicine, Taoyuan,
Taiwan
2 Chang Gung Memorial Hospital, Section of Head and
Neck Surgery- Department of Otorhinolaryngology,
Taoyuan, Taiwan
3 Chang Gung Memorial Hospital, Department of Nuclear
Medicine and Molecular Imaging Center, Taoyuan,
Taiwan
4 ACT Genomics, Taipei, Taiwan
5 Chang Gung Memorial Hospital, Department of
Pathology, Taoyuan, Taiwan
6 Chang Gung Memorial Hospital, Department of
Radiation Oncology, Taoyuan, Taiwan
7 Chang Gung Memorial Hospital, Department of
Diagnostic Radiology, Taoyuan, Taiwan
Purpose or Objective
Patients with resected oral squamous cell carcinoma
(OSCC) harboring metastatic lymph node without
extracapsular spread (ECS) show heterogeneous
outcomes. We aim to improve their prognostic
stratification by combining the traditional
clinicopathological prognosticators with the genetic
information obtained from next-generation sequencing
(NGS).
Material and Methods
The hotspot mutation regions of 45 cancer-related genes
were investigated using NGS with an ultra-deep (>1000×)
sequencing approach in formalin-fixed paraffin-embedded
samples obtained from 144 patients who had resected
OSCC harboring neck lymph node without ECS.
Results
Pathologic T4 was the most important traditional
prognosticators for disease-specific survival (DSS). The 5-
year DSS for patients with pT4 versus pT1-3 was 48.8%
versus 80.2% (P < 0.001). Multivariate analysis in patients
with pT1-3 (n = 101) identified the following adverse
prognostic factors: 1) HRAS/BRAF mutation (n = 7) for
distant metastasis (DM) (27% versus 7%, P = 0.006) and DSS
(57% versus 82%, P = 0.005); and 2) TP53 DNA-binding
domain missense mutations (n = 38) for DM (13% versus 3%,
P = 0.053) and DSS (68% versus 90%, P = 0.004). The
prognosticators in patients with pT4 (n = 43) were: 1)
Lymph node number ≥3 (n = 10) for locoregional failure
(70% versus 33%, P = 0.032) and DSS (30% versus 55%, P =
0.050); 2) HRAS/BRAF mutation (n = 6) for DM (67% versus
14%, P = 0.008) and DSS (0% versus 57%, P = 0.001); and 3)
no adjuvant radiotherapy (n = 2) for DSS (0 versus 51%, P
= 0.013).
Conclusion
Genetic information from NGS may improve the prognostic
stratification offered by traditional prognosticators in
resected OSCC patients harboring metastatic lymph node
without ECS. Our findings will contribute to
implementation of precision medicine in OSCC patients.
PV-0508 Prognostic significance of PD-L1 expression
in patients with head and neck squamous cell
carcinoma
C. Peng1, X. Gu1, X.S. Gao 1, X. Li1, S. Qin1, M. Ma1, M.
Cui1, M. Xie1, Y. Bai1
1Peking University First Hospital, Department of
Radiation Oncology, Beijing, China
Purpose or Objective
Previous studies have investigated the association
between programmed death ligand-1 (PD-L1) expression
and survival of patients with head and neck squamous cell
carcinoma (HNSCC). However, the results were
controversial and inconclusive. We therefore conducted a
meta-analysis of published studies to evaluate the
prognostic significance of PD-L1 expression in HNSCC.
Material and Methods
Relevant studies were retrieved through PubMed, Web of
Science, Embase, Cochrane Library, China National
Knowledge Infrastructure (CNKI). Combined hazard ratio
(HR) and 95% confidence interval (CI) were calculated to
assess the association between PD-L1 and overall survival
(OS), progression-free survival (PFS)/ disease-free survival
(DFS), cancer-specific survival(CSS). ORs with 95% CIs were
calculated to evaluate the relationship between PD-L1
status and clinicopathological factors. Subgroup analyses
and publication bias were also conducted.
Results
A total of 12 studies (13 cohorts) with 1777 patients were
ultimately included in the meta-analysis. Results showed
that high PD-L1 expression predicted poor CSS in HNSCC
(HR 1.472, 95%CI: 1.013-2.138). Stratification analyses
revealed that high PD-L1 expression was associated with
poor OS in Asians (HR= 1.301; 95% CI:1.056-1.602) and oral
SCC (HR=1.343; 95% CI:1.071-1.685) patients. In addition,
we observed that high PD-L1 expression was correlated
with female patients (OR=0.638, 95% CI: 0.478-0.853),
lymph node metastasis (OR=1.415, 95% CI: 1.082-1.85),
nonsmokers (OR=0.753, 95% CI: 0.569-0.995), HPV positive
patients (OR=1.523, 95% CI: 1.032-2.247) in HNSCC.