Outcomes of re-irradiation & repeat radiotherapy in NSCLC: A propensity matched analysis
Sandhu, L McWilliam, Alan Mistry, H. Woolf, David K Golby, C Abravan, Azadeh Van Herk, Marcel Price, G Salem, Ahmed
Sandhu, L
McWilliam, Alan
Mistry, H.
Woolf, David K
Golby, C
Abravan, Azadeh
Van Herk, Marcel
Price, G
Salem, Ahmed
Citations
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Abstract
Purpose or Objective
Non-small cell lung cancer (NSCLC) locoregional
recurrence and second primary are common after
(chemo)radiotherapy could be treated with re-irradiation
(same area) and repeat radiotherapy (different area),
respectively. Our aims were to investigate the outcomes
of NSCLC patients treated with re-irradiation and repeat
radiotherapy and compare to a matched cohort. Material
and Methods
NSCLC patients who received two curative-intent thoracic
radiotherapy courses in the Christie NHS Foundation Trust
(Manchester, UK) [FC(NC1] were retrospectively analysed
(2013-2019). Radiotherapy plans were rigidly coregistered,
if available, to quantify treatment field
overlap and differentiate re-irradiation from repeat
radiotherapy. Re-irradiation was designated if >0.5cm3 of
the thoracic region received a radiotherapy dose higher
than the maximum dose delivered in either of the two
radiotherapy plans. A NSCLC patient group who received a
single course of curative-intent thoracic radiotherapy was
utilized to generate a matched cohort based on age,
gender, radiotherapy type (stereotactic ablative
radiotherapy (SABR) vs fractionated intensity modulated
radiotherapy (IMRT)), TNM stage and ECOG performance
score. Logistic regression was used to create a propensity
score model. The primary endpoint was overall survival
(OS).
Results
79 NSCLC patients (median age: 75) underwent two
curative-intent thoracic radiotherapy courses
(retreatment cohort). The second radiotherapy treatment
(RT2) was SABR in 27 and fractionated IMRT in 52 patients.
The tumour stage at RT2 was: stage I (n=47), stage II (n=7),
stage III (n=7), stage IV (n=3) and unknown (n=15). The
median prescribed dose (peaked for SABR) for the RT1 and
RT2 was 57Gy (range: 45-88) and 57Gy (range: 54-60),
respectively. Table 1 shows characteristics for the
retreatment and matched cohort (n=77). The median OS
(measured from RT1) for the retreatment cohort was 51m
(95% CI: 45-58); fig1A. The median OS was 51m (95%CI: 49-
NA) for patients treated with re-irradiation (n=25) and 58m
(95%CI: 51-NA) for patients treated with repeat
radiotherapy (n=28). After adjusting for lead time bias (OS
measured from RT2), patients who underwent retreatment
within 1y of the first radiotherapy had worse OS (median:
20m, 95% CI: 12-36) compared to patients where the interradiotherapy
gap was >1y (median: 25m, 95% CI: 15-55);
p=0.013 (fig1B). The type of radiotherapy and
performance score were not prognostic in the retreatment
cohort. After adjusting for lead time bias, there was no
difference in OS for the retreatment (median: 21m, 95%
CI: 15-33) and the matched cohort (median: 22m, 95%CI:
17-NA); p=0.436 Conclusion
The lack of survival difference between retreatment and
matched cohorts provide indirect evidence of the benefit
of a second curative-intent thoracic radiotherapy course in
NSCLC patients with locoregional recurrence and second
primary. Prospective trials are needed to standardise
retreatment dose and investigate toxicity and quality of
life.
Description
Date
2020
Publisher
Collections
Keywords
Type
Meetings and Proceedings
Citation
Sandhu L, McWilliam A, Mistry H, Woolf D, Faivre-Finn C, Golby C, et al. PH-0281: Outcomes of re-irradiation & repeat radiotherapy in NSCLC: A propensity matched analysis. Radiotherapy and Oncology . 2020 Nov;152:S141–2.