Background:
Stereotactic radiosurgery (SRS) is the gold standard for treatment of small and medium
sized tumours, although fractionated regimens are well described. Access is limited in
resource-constrained settings. There are no South African data describing outcomes of AN
patients treated with fractionated stereotactic radiotherapy (SRT) using photons. We
describe clinical and radiological outcomes of AN patients treated with SRT at an academic
centre in Cape Town, South Africa.
Objectives:
To describe patient demographics, tumour characteristics and patients’ symptoms and
changes in symptoms at follow-up. To investigate tumour local control (LC) rates at last
follow up MRI, and compare LC rates described for SRS in the literature. To correlate
radiologists’ serial 2D maximum linear diameter (MLD) measurements with calculated 3D
tumour volume (TV).
Methods:
Fifteen AN patients treated with modified SRT (18.0gy/3fractions, were identified from the
planning database; 13 were included. Patient data and tumour characteristics (size, laterality
and previous surgery) were retrospectively extracted from clinic folders. Initial planning data
was accessed and checked. Tumour volumes were contoured by the author on all
subsequent MRI’s per patient and validated by a second investigator; tumour volume (TV)
was automatically calculated. Radiologist’s 2D MLDs were compared with 3D TV. Sensitivity
and specificity of radiologist reported change of MLD as a measure of actual change in TV
was calculated. LC was calculated, from time of treatment to time of last MRI or time of
progression (defined as ≥20% increase in TV).
Results:
Mean age was 60.4years (range 45-79years), with 4 (30.8%) being female. Seven patients
(53.8%) had left sided tumours and median tumour size was 1.15cm3 (mean 1.59 cm3; range
0.62-3.35 cm3). Nine patients (69.2%) had Koos stage 2 ANs, 3 (23.1%) had stage 3
tumours and 1 (7.7%) had a stage I tumour. Two patients had NF2.Median follow-up time
12 was 29 months (range 0-50 months). Median baseline TV, as was 1.15 cm3 (mean 1.59cm3
with range 0.62-3.35 cm3).
Three patients had no follow-up MRIs: 2 demised and 1 declined further follow-up. In total 5
patients died, 4 of unrelated causes and 1 of unknown cause (median time to death after RT
24 months, range 6 - 36 months). LC was 74% at 36months. Hearing preservation rate was
67%. No new facial or trigeminal nerve symptoms were noted. Radiologists correctly
reported tumour growth in 100% of tumours that grew, and specificity was 77.3% in those
that were stable.
Conclusion:
This is the first local study in hypofractionated SRT using photons. We show lower LC rates
than seen in literature; our numbers are small and short follow up time short, with high
attrition rates. Acute treatment toxicities were absent. Longer term follow-up is needed to
assess late RT effects. A prospective study using this method of treatment would better
define LC.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uct/oai:localhost:11427/30174 |
| Date | 17 May 2019 |
| Creators | Riddick, Alison |
| Contributors | Parkes, J, Burger, Hester |
| Publisher | Faculty of Health Sciences, Division of Radiology |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Master Thesis, Masters, MMed (Radiation Oncology) |
| Format | application/pdf |
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