Clinicoradiological outcomes after radical radiotherapy for lung cancer in patients with interstitial lung disease

OBJECTIVE: Interstitial lung disease (ILD) is relatively common in patients with lung cancer with an incidence of 7.5%.

Historically pre-existing ILD was a contraindication to radical radiotherapy owing to increased radiation pneumonitis rates, worsened fibrosis and poorer survival compared with non-ILD cohorts.

Herein, the clinical and radiological toxicity outcomes of a contemporaneous cohort are described.

METHODS: Patients with ILD treated with radical radiotherapy for lung cancer at a regional cancer centre were collected prospectively.

Radiotherapy planning, tumour characteristics, and pre- and post-treatment functional and radiological parameters were recorded.

Cross-sectional images were independently assessed by two Consultant Thoracic Radiologists.

RESULTS: Twenty-seven patients with co-existing ILD received radical radiotherapy from February 2009 to April 2019, with predominance of usual interstitial pneumonia subtype (52%).

According to ILD-GAP scores, most patients were Stage I.

After radiotherapy, localised (41%) or extensive (41%) progressive interstitial changes were noted for most patients yet dyspnoea scores (n = 15 available) and spirometry (n = 10 available) were stable.

One-third of patients with ILD went on to receive long-term oxygen therapy, which was significantly more than the non-ILD cohort.

Median survival trended towards being worse compared with non-ILD cases (17.8 vs 24.0 months, p = 0.834).

CONCLUSION: Radiological progression of ILD and reduced survival were observed post-radiotherapy in this small cohort receiving lung cancer radiotherapy, although a matched functional decline was frequently absent.

Although there is an excess of early deaths, long-term disease control is achievable.

ADVANCES IN KNOWLEDGE: For selected patients with ILD, long-term lung cancer control without severely impacting respiratory function may be possible with radical radiotherapy, albeit with a slightly higher risk of death.