Impact of introducing IMRT on curative intent radiotherapy and survival for lung cancer
Clara Chan,
United Kingdom
OC-0437
Abstract
Impact of introducing IMRT on curative intent radiotherapy and survival for lung cancer
Authors: Clara Chan1, Isabella Fornacon-Wood2, Neil Bayman1, Kathryn Banfil1, Joanna Coote1, Alex Garbett3, Margaret Harris1, Andrew Hudson1, Jason Kennedy4, Laura Pemberton1, Gareth Price5, Ahmed Salem6, Hamid Sheikh1, Philip Whitehurst5, David Woolf1, Corinne Faivre-Finn6
1The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom; 2University of Manchester, Institute of Cancer Sciences, Manchester, United Kingdom; 3The Christie NHS Foundation Trust, Analytics, The Christie NHS Foundation Trust, United Kingdom; 4The Christie NHS Foundation Trust, Radiation Related Research, Manchester, United Kingdom; 5The Christie NHS Foundation Trust, Medical Physics and Engineering, Manchester, United Kingdom; 6The University of Manchester, Institute of Cancer Sciences, Manchester, United Kingdom
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Purpose or Objective
Lung cancer survival remains poor. The introduction of
Intensity-modulated radiotherapy (IMRT) has allowed treatment of more complex
tumours as it improves radiotherapy dose conformity and normal tissue sparing.
However, implementation of IMRT for the curative-intent treatment of lung
cancer has lagged behind that of other disease sites and there is limited
evidence in the literature assessing the clinical impact of IMRT. In this study, we evaluated whether the
introduction of IMRT has had an influence on the proportion of patients treated
with curative-intent radiotherapy, and whether this has had an effect on
patient survival.
Material and Methods
Patients with lung cancer treated with thoracic
radiotherapy at our institute between 2005-2020 were retrospectively identified
and grouped into three time periods: A) 2005-2008 (pre-IMRT), B) 2009-2012
(some availability IMRT), and C) 2013-2020 (full access IMRT). Data on
performance status (PS), stage, age, gross tumour volume (GTV), planning target
volume (PTV) and survival were
collected. The proportion of patients treated with a curative dose (>40Gy)
between these periods was compared. Multivariable survival models were fitted
to evaluate the hazard for patients treated in each time period, adjusting for
PS, stage, age and tumour volume.
Results
12,499 patients were included in the analysis (n=2675
(A), n=3127 (B), and n=6697 (C)). The proportion of stage patients treated with
curative-intent radiotherapy increased between the 3 time periods, from 38.1%
to 50.2% to 65.6% (p<0.001). When stage IV patients were excluded, this
increased to 40.1% to 58.1% to 82.9% (p<0.001). This trend was seen across
all PS and stages, and was still upheld when SABR patients were excluded from
the analysis. The GTV increased across the time periods (median GTV 35.5 cm3
[16.8, 60.1], 41.7 cm3 [16.3, 85.8] and 47.6 cm3 [17.6,
112.1] for groups A, B and C excluding SABR patients respectively, p<0.01)
although the PTV volume did not. Curative-intent patients treated during period
C had a survival improvement compared to time period A when adjusting for
clinical variables (all stages HR=0.725 (0.632-0.831), p<0.001; stage III
patients HR=0.740 (0.600-0.913), p<0.005).
Conclusion
This real world, big data analysis has shown that the
introduction of IMRT was associated with more patients receiving curative-intent
radiotherapy across all PS and stages of disease. In addition it facilitated
the treatment of larger tumours that historically would have been treated
palliatively. Despite treating larger, more complex tumours with
curative-intent, a survival benefit was seen for patients treated when full
access to IMRT was available. We acknowledge that other contributing factors
such as improvement in staging and systemic therapy may have also contributed
to the improved survival.