Radiation Pneumonitis Timing — RACP Adult Medicine MCQ

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ModerateRespiratoryRadiation Pneumonitis TimingRACP Adult Medicine

A 60-year-old man with stage IIIA non-small cell lung cancer undergoes concurrent chemoradiation and completes 12 months of durvalumab consolidation (PACIFIC protocol). Two years later, he develops radiation pneumonitis. What is the typical time course for radiation pneumonitis?

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Correct answer: E — Radiation pneumonitis only occurs during treatment

Radiation pneumonitis typically develops 1–6 months after completing thoracic radiation (peak incidence 2–3 months). It presents with cough, dyspnoea, low-grade fever, and new ground-glass/consolidative changes on CT confined to the radiation field (though can extend beyond). Risk factors include: large radiation volume, concurrent chemotherapy, pre-existing ILD, and concurrent ICI (durvalumab – PACIFIC trial reported ~34% any-grade pneumonitis). Late radiation fibrosis (>6 months) is a separate entity characterised by permanent scarring. Treatment of acute radiation pneumonitis is oral prednisolone (1 mg/kg, slow taper over 6–12 weeks). Two years post-radiation would be unusually late for acute pneumonitis – late fibrosis or ICI-related pneumonitis should also be considered in this patient.

Reference: eTG – 2025 – Respiratory; Cancer Council Australia – 2021 – Lung Cancer OCP