Abstract 423P
Background
Interstitial lung abnormalities (ILA) are pre-clinical radiological features with a 20–40% risk of progression to interstitial lung disease (ILD). Limited evidence has shown high toxicity and poor survival after lung radiotherapy in patients with ILD and no evidence exists for ILA.
Methods
Patients with stage I-III non-small cell lung cancer treated with curative-intent (chemo)radiotherapy from 06/2016–06/2023 were included in a retrospective analysis. Those with a previous diagnosis of ILD or radiological descriptors suggestive of ILA on pre-radiotherapy CT reports were identified. ILD radiologists classified patients into ILD or possible ILD, ILA or no conclusive features. Demographics, lung function, treatment, toxicity, progression-free (PFS) and overall survival (OS) were collected. Kaplan-Meier curves and log-rank tests were used for survival comparisons. A multivariable analysis (MVA) was performed including patients with ILD or ILA, to evaluate the effect of age, performance status, lung function, planned target volume (PTV) on OS.
Table 423PDemographics and treatment
| ILD n=53 | ILA n=53 | No features n=57 | |
| Median Age | 74 | 74 | 75 |
| Stage | |||
| Stage 1 | 25 | 30 | 28 |
| Stage 2 | 11 | 4 | 6 |
| Stage 3 | 17 | 19 | 23 |
| Performance Status | |||
| 0 | 2 | 2 | 6 |
| 1 | 22 | 19 | 20 |
| 2 | 25 | 24 | 24 |
| 3 | 4 | 8 | 7 |
| Radiotherapy | |||
| SABR | 21 | 27 | 22 |
| Conventional | 32 | 30 | 35 |
| Chemotherapy | |||
| Yes | 6 | 7 | 13 |
| No | 47 | 46 | 44 |
Results
163 patients were included. Median follow-up was 32.5 months. A significant difference in grade 5 pneumonitis was identified between patients with ILD, ILA vs no features (7, 3 and 0 events, p=0.009). There was also a significant difference in PFS (9.2, 12.8, 13.1 months, p=0.018), and OS (9.5, 14.7 and 22.5 months, p=0.001). On MVA including 88 patients, ILA was associated with improved survival (HR 0.55 95% CI 0.32–0.94, p=0.03), while PTV was associated with worse survival (HR 1.003 95% CI 1.001–1.004, p ≤ 0.0001), after adjusting for other risk factors.
Conclusions
Patients with ILA prior to radiotherapy exhibit more favourable toxicity and survival outcomes compared to those with ILD. Further research is required to optimise treatment for patients with ILA/ILD. Implementing AI-based screening for early detection of ILA/ILD would be a valuable next step.
Legal entity responsible for the study
Radiotherapy Related Research Group, The Christie NHS Foundation Trust.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.