1. Factors affecting Facial Asymmetry in Children Irradiated
For Embryonal Rhabdomyosarcoma of the Orbit
Marinka L.F. Hol, MD1; Daniel J. Indelicato, MD2; Ronny L. Rotondo, MD2;
Raymond B. Mailhot Vega MD, MPH2; Haruka Uezono, MD2; Julie A. Bradley, MD2 1Amsterdam UMC, The Netherlands 2University of Florida, United States
BACKGROUND AND PURPOSE
MATERIALS AND METHODS
2006 to 2018: 1,657 pediatric patients treated at UF Health
17 survivors with COG group 1 stage 3 orbital ERMS
MRI available at >6 months follow-up
No previous treatments in the head and neck area
1 patient excluded for a tumor still largely in situ
With the ongoing improvement in long-term survival among patients with paediatric embryonal rhabdomyosarcoma (ERMS), the impact of adverse late effects becomes more prominent. In patients with orbital tumors, these late effects include poor cosmesis associated with facial deformation and facial asymmetry. Our purpose was to assess orbital volume (OV) changes in patients treated for orbital ERMS and to characterize the dose effect for orbital bones.
Orbital Volume Calculation
PATIENTS AND TREATMENT CHARACTERISTICS
OV was measured on the MRI
Use: axial slice with the maximum size of lens
Anterior-posterior depth: the lens to deepest part of the bony orbit
Width: the most anterior part of the zygomatic bone to the posterior part nasal bone
For the volume calculation, the orbit was considered a cone
Radiotherapy
All patients were treated to a dose of 45 GyRBE in 1.8 fractions with protons delivered in 2 sequential phases. All patients were treated with double-scattered proton plans using 2 to 3 beams per phase.
Factors affecting Orbital Volume
Baseline Characteristics
N = 16
Age at diagnosis
Mean (range)
5.4 yrs ( yrs)
Follow-up time
2.9 yrs (0.8 – 3.2 yrs)
Age at scan
8.4 yrs (2.3 – 12.9yrs)
Sex
Male
Female
10 (63%)
6 (37%)
Chemotherapy protocol
ARST0331
D9602
RMS2005
1 (6%)
9 (56%)
Patient age, orbital tumor quadrant, and the maximum radiation dose delivered to the major orbital bones (maxillary bone, frontal bone,and zygomatic bone) were recorded and correlated with orbital volume differentials.
Example of left orbital hypoplasia in RMS survivor
RESULTS
Orbital Volume
Radiation Dose-effect
N=16
Radiated side
Non-radiated side
Statistical significance
Orbital volume
11 cm3
Range: 5.3 – 17.3 cm3
12.9 cm3
Range: 7.4 – 17.9 cm3
P<0.005
N=16
Mean dose
Range
Correlation OV differential
Frontal bone
41.9Gy Gy
0.32
Zygomatic bone
40.8Gy Gy
0.15
Maxillary bone
41Gy Gy
0.22
Orbital rim combined
41.25Gy
0.47
N=16
Mean difference
Over 1 cm3
Over 2 cm3
Orbital volume differential
1.9 cm3 (1.0 – 4.9 )
75%
41%
Orbital Volume Differential and Time
The OV differential did not correlate with age at treatment (R=-0.2, p=0.8).
The OV differential moderately correlated with the amount of follow-up time (R=0.49, sig lev P=0.02), with notable volume differential observed in patients with a follow-up time over 4 years (p=0.017).
The OV differential did not correlate with age at the follow-up scan (R=0.01).
CONCLUSIONS
Over 75% of orbital ERMS survivors will demonstrate orbital volume asymmetry.
Differential in orbital volume most affected by a combined radiation dose of >40 Gy to all orbital rim bones. Isolated high radiation dose to any of the orbital rim bones did not impact orbital volume at early follow-up.
These data may be used to guide treatment planning and counsel patients on expected cosmesis.
Corresponding Author: Daniel J. Indelicato, MD,