Radiotherapy for the treatment of pain in malignant pleural mesothelioma
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Date
02/07/2016Author
MacLeod, Nicholas James Lewis
Metadata
Abstract
Aims: The primary aim of this thesis was to explore the role of palliative
radiotherapy in the treatment of pain in malignant pleural mesothelioma (MPM).
The effect of radiotherapy on other symptoms was also examined. Biomarkers
which might predict response to radiotherapy (Quantitative Sensory Testing –
QST) were explored and objective evidence of response was sought via
interpretation of Computed Tomography (CT) scans. The thesis also examined
the role of Positron Emission Tomography (PET)-CT in radiotherapy planning
and characterising pain in MPM.
Methods: A narrative review of the challenges of pain management in MPM and
a systematic review of the evidence supporting the use of palliative radiotherapy
for pain control in MPM, were undertaken. In addition, a multi-centre, single arm
phase II trial was conducted which examined the role of radiotherapy in pain
control in MPM. This trial also assessed the role of PET-CT in radiotherapy
planning and allowed for a characterisation of MPM-related pain. These
components form the basis of this thesis.
Results: Palliative radiotherapy at a dose of 20 Gy in five daily fractions using 6
Megavoltage (MV) photons improves pain in a significant proportion of patients
with MPM. It does not have a beneficial effect on other symptoms or on quality
of life. QST does not appear to be a useful clinical biomarker indicating
likelihood of response to radiotherapy. Objective evidence of response via CT is
low. Incorporation of PET-CT in the radiotherapy planning process alters the
anatomical location of the target volume in patients with MPM. There is also an
association between the Standard Uptake Value (SUV) uptake and pain, with the
areas with highest SUV uptake being associated with the areas of pain. PET-CT results in upstaging of a significant proportion of patients. Pain is often severe
and debilitating for patients with MPM and it has often a combination of
neuropathic and nociceptive mechanisms. The presence of a neuropathic
component to the pain is not associated with an increased likelihood of response
to radiotherapy.
Conclusions: Radiotherapy is effective at relieving pain in a proportion of
patients with MPM and should be considered for all patients with MPM-related
pain. PET-CT improves multiple parameters in the radiotherapy planning process
compared with CT alone. QST parameters have not been shown to predict those
patients who are likely to respond to radiotherapy.