ESTRO 36 Abstract Book

S176

ESTRO 36

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Data and tumor tissue from 815 patients enrolled in 4 trials

(DAHANCA 6-7, RTOG 9003, ARTSCAN, RTOG 0129) was

available for analysis: 350 (43%) HPV-neg and 465 (57%)

HPV-pos. Patients with HPV-pos tumors were significantly

younger (mean: 56 vs 59 years, p=0.0002), in better

performance status (PS=0: 74% vs 50%, p<0.0001), had

smaller tumors (T1-2: 46% versus 33%, p<0.0001) and more

advanced N-stage (N+: 87% versus 76%, p<0.0001)

compared with the HPV-neg subgroup. HPV-status

significantly influenced prognosis and HPV-pos patients

had favorable PFS (HR=0.42 [95% CI: 0.34-0.51] with a 42%

absolute increase at 10 years) and OS (HR=0.40 [0.32-0.49]

with a 40% absolute increase at 10 years) compared to the

HPV-neg subgroup. Smoking independently influenced

outcome and never/former smokers had better prognosis

than current smokers with HR of 0.61 [0.50-0.75] and 0.58

[0.47-0.72] for PFS and OS, respectively. A further analysis

of the impact of smoking was performed classifying

smoking as former/current vs never smokers. This

consequently led to the exclusion of 166 patients from the

ARTSCAN trial where this information was not available.

Compared to the HPV-neg smoking subgroup, HPV-pos

never smokers were found to have significantly better

outcomes (PFS: HR: 0.20 [0.14-0.31] and OS: HR: 0.20

[0.13-0.31]). Similar, although less pronounced, survival

benefits were observed for HPV-pos smokers (PFS: HR:

0.41 [0.33-0.51] and OS: HR: 0.38 [0.30-0.47]) when

compared with HPV-neg smokers. There was no significant

interaction between HPV-status and fractionation effect,

whatever the coding for smoking.

Conclusion

HPV status was not found to be predictive of outcome

after altered fractionated RT in this pooled analysis of

OPC. However, the strong prognostic impact of HPV was

confirmed and especially HPV-pos never smoking patients

have superior outcome after RT.

Supported by the French Ministry of Health (PHRC)

OC-0334 Prospective MR assessment of dose-response

kinetics of non-target muscles in head and neck cancer

A.S.R. Mohamed

, R. Davuluri

, S. Frank

, Y. Ding

, S.

Lai

, J. Wang

, C. Fuller

, K. Hutcheson

The University of Texas- MD Anderson Cancer Center,

Radiation Oncology, Houston, USA

Purpose or Objective

We have recently demonstrated the role of Magnetic

Resonance Imaging (MRI) in characterizing radiotherapy

(RT)-induced changes in non-target swallowing related

musculature in a retrospective head and neck cancer

cohort treated with definitive RT. We aim to validate the

longitudinal dose-response changes of normal-muscle

quantitative MRI signal kinetics in a prospective and well

curated institutional dataset.

Material and Methods

A total of 39 patients were enrolled as part of an ongoing

prospective clinical trial after obtaining study specific

signed consent. All patients underwent three MRI studies:

pre-, mid-, and post-RT. The mean T1, T1+ contrast

(T1+C), and T2-weighted signal intensities (SI) for superior

pharyngeal constrictors (SPC), middle pharyngeal

constrictors (MPC), intrinsic tongue muscles (ITM),

geniohyoid (GH), genioglossus (GG), mylohyoid (MH),

masseters, medial/lateral pterygoids, anterior/posterior

digastrics (ADM, PDM), and buccinators were recorded in

the three time points and delta SI changes were

calculated. Trapezius muscle was segment as a control

due to negligible dose received. The SI changes were

correlated to RT dose to the segmented structures after

deformable image registration to planning CT and dose.

Results

All patients were stage III-IV HPV-positive oropharyngeal

cancer. Median age was 58 years (range 39-80), 35 (90%)

were men, and 35 (90%) were white race. Tonsillar fossa

was the area of tumor origin in 20 patients (51%) and base

of tongue in 19 (49%). Prescription dose was 70 Gy in 33

fractions. At mid-RT; significant increase in mean T1+C SI

was noted in the following muscles: ADM, ITM, GHM, and

MPC (p=0.005, 0.01, 0.04, and 0.002, respectively) and

significant increase in mean T2 SI was noted only in MPC

(p=0.0005). At post-RT; significant increase in mean T1+C

SI was detected in all studied muscles (p<0.05 for all).

After Bonferroni correction for multiple comparisons, all

remained significant except buccinators, pterygoids, and

masseter. Post-RT increase in T2 SI was detected only in

pharyngeal constrictors and medial pterygoids (p<0.05)

and remained significant after Bonferroni correction for

pharyngeal constrictors. No significant changes in mean T1

SI was detected in all tested muscles in both time points.

There were no dose-parameter relationship in all muscles

with increased T1+C and T2 SIs in all studied time points.

Mean dose to muscle groups with significant increase in

T1+C after Bonferroni correction was significantly higher

compared to other muscle groups (52.7 vs. 37.5 Gy,

p<0.0001). Simultaneously, mean dose to pharyngeal

constrictors that showed significant T2 increase was

significantly higher compared to other muscle groups (63.2

vs. 41.2 Gy, p<0.0001).

Conclusion

Significant dose-dependent increase in mid-RT and post-

RT T1+C and T2 signal intensities is noted in non-target

swallowing muscles particularly in pharyngeal constrictors

due to higher beam-path dose to these muscles.

Symposium: GTFRCC

SP-0335 GTFRCC: where to go from here?

Y. Lievens

University Hospital Ghent,

Department of Radiation Oncology, Gent, Belgium

The Global Task Force on Radiotherapy for Cancer Control

(GTFRCC) has not only highlighted the urgent need for

addressing the inequity gap in access to radiotherapy

globally, it has also demonstrated that judicious

investment in radiotherapy infrastructure and training is

both effective and cost-effective. Indeed, in addition to

preventing millions of cancer deaths in the decades to

come, investing in radiotherapy has also been shown to

bring value for money and a positive return on investment

to the societies involved. The GTFRCC has articulated five

calls-to-action in order to remedy the radiotherapy

shortage and to make sure that radiotherapy is included

into the multidisciplinary approach to cancer care.

To ascertain a global impact by 2035, the time is now to

build upon the GTFRCC results. ESTRO and the

stakeholders involved in the GTFRCC have decided to join

forces by establishing a new collaborative group with the

aim of identifying timely, effective, and achievable

responses to the GTFRCC’s calls-to-action, and of

positioning radiotherapy as an essential component of

effective cancer care globally. It is our pleasure to launch

this initiative at ESTRO 36!

SP-0336 Costs and needs of radiotherapy: a regional

perspective

E.H. Zubizarreta - zubi

IAEA, Applied Radiation Biology and Radiotherapy,

Wien, Austria

This analysis presents the resources needed and costs at

the present time globally and by region to give full access

to RT. The variables and methodology were the same used

by the GTFRCC. The GTFRCC reported the resources

needed and costs to reach full access to RT in 2035 by

income group, but not per region (Atun R et al. Expanding

global access to radiotherapy. Lancet Oncol 2015; 16(10)).

The division in regions adopted by the IAEA was used:

Africa (AF), North America (NA) only includes USA and