Impact of introducing IMRT on curative intent radiotherapy and survival for lung cancer
Chan, Clara Fornacon-Wood, Isabella Banfill, Kathryn Coote, Joanna H Garbett, Alexander Harris, Maggie A Hudson, Andrew M Kennedy, Jason Pemberton, Laura S
Chan, Clara
Fornacon-Wood, Isabella
Banfill, Kathryn
Coote, Joanna H
Garbett, Alexander
Harris, Maggie A
Hudson, Andrew M
Kennedy, Jason
Pemberton, Laura S
Citations
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Abstract
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.
Materials 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.
Description
Date
2022
Publisher
Collections
Keywords
Type
Meetings and Proceedings
Citation
Chan C, Fornacon-Wood I, Bayman N, Banfil K, Coote J, Garbett A, et al. Impact of introducing IMRT on curative intent radiotherapy and survival for lung cancer. Radiotherapy and Oncology. 2022 May;170:S380-S1. PubMed PMID: WOS:000806764200031.