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Case details are given in Table 1. Oral cavity primary
disease accounted for 15% of cases in the original cohort
available for review (prior to exclusions), but half of
patients who relapsed loco-regionally. Mean time to
relapse was 18 weeks (Std. error +/- 2.4 weeks). 10 of 12
patients (83%) had residual or relapsed disease ipsilateral
to the primary site. 2 (both lateral tongue SCCs who
underwent primary surgery followed by RT +/- chemo to
the primary site and ipsilateral neck) relapsed early (8 and
20 weeks respectively) in the contralateral, un-irradiated
neck.
Figure 1 describes the volume of rGTV covered by
pertinent isodose contours and target CTV/PTVs.
According to our criteria, 9 of 12 relapses were in-field
(75%), 1 (8.3%) was marginal and 2 (16.7%) were in
deliberately un-irradiated contralateral neck nodes as
described.
Conclusion
Oral cavity tumours appeared at highest risk of relapse in
our cohort. Using DIR to map disease relapse to treatment
volumes and dose, we found most relapsed HNSCC (75%)
occurred within the high dose volume, in keeping with
previous studies, and suggesting that unfavourable biology
rather than inadequate RT is the predominant reason for
loco-regional HNSCC relapse. Our results will be used to
inform review of our neck irradiation policy, particularly
for SCCs of the oral cavity.
EP-1097 P16 expression: a predictive marker for
treatment-related outcomes in oropharyngeal cancer
patients?
A. Modesto
1
, T. Galissier
2
, A. Lusque
3
, E. Uro-Coste
2
, J.
Delord
4
, A. Laprie
1
, J. Sarini
5
, P. Graff
1
, P. Vergez
5
, M.
Rives
1
1
Institut Universitaire du Cancer, radiation therapy,
Toulouse, France
2
Institut Universitaire du Cancer, Pathology, Toulouse,
France
3
Institut Universitaire du Cancer, Biostatistics, Toulouse,
France
4
Institut Universitaire du Cancer, Medical Oncology,
Toulouse, France
5
Institut Universitaire du Cancer, Head and Neck
Surgery, Toulouse, France
Purpose or Objective
Treatment strategies in oropharyngeal squamous cell
carcinomas (OSCC) consist in either surgery followed by
adjuvant
radio(chemo)therapy
or
definitive
radio(chemo)therapy. P16 overexpression (p16+) is
considered as a surrogate marker for HPV-induced tumors
that are associated with improved outcome whichever
treatment modality is considered in comparison with p16
negative (p16-) OSCC. To date no predictive factors are
known to guide treatment decision.
Material and Methods
All consecutive patients treated for an OSCC with a
curative intend at a single tertiary cancer center between
2009 and 2013 were eligible to this study. P16 status was
determined by immunochemistry and centrally reviewed.
Late toxicities incidence ie: dysphagia, xerostomia,
painful shoulder, osteoradionecrosis or nerve paralysis
were registrated and graded according to CTCAE v4 in
patients alive without loco-regional evolution at least 6
months after treatment completion. Three-year disease
free survival (DFS) and late severe toxicity occurrence
were compared according to p16 expression and
treatment modality: initial surgical treatment or
definitive radio(chemo)therapy.
Results
Among the 167 patients included in this study, 77 (44%)
presented a tumoral p16 overexpression (p16+). Initial
surgery was performed in 51 (66%) and 48 (53%) cases and
definitive radiochemotherapy was performed in 26 (34%)
and 42 (47%) cases among p16 + and p16 - patients
respectively (p=0.05). 99 patients (60%) underwent initial
surgery followed by adjuvant radio (chemo) therapy in 51
cases (91 %). After a 51-month of median follow-up [47-54
months], the 3-year DFS was 82% and 42% among overall
p16 + and p16 - patients respectively (p=0.01). Among p16
– patients, the 3-year DFS after initial surgery or definitive
radiochemotherapy was 62% and 32% respectively
(p=0.003). Among p16 + patients, the 3-year DFS was 85%
and 77% (p=0.16) whereas severe delayed toxicity
occurred in 42% vs. 18% after initial surgery or definitive
radiochemotherapy respectively (p=0.05).
Conclusion
Whereas p16- OSSC are at high risk of loco-regional failure
and highly benefited from aggressive multimodal
treatment
including
surgery
and
adjuvant
radio(chemo)therapy, p16+ OSCC didn’t harbour the same
benefit from the combinative approach that was
associated with a significant increase of delayed severe
toxicity. The benefit of initial surgery or definitive
radio(chemo) therapy seemed not equivalent among OSSC
patients according to p16 status that might be a useful
tool
to
guide
initial
treatment
decision.