Radiation recall pneumonitis caused by erlotinib after palliative definitive radiotherapy

Radiation recall pneumonitis (RRP) occurs in a previously irradiated field and is triggered by certain cytotoxic drugs, principally chemotherapeutic agents such as erlotinib. Erlotinib is a reversible epidermal growth factor receptor tyrosine kinase inhibitor (TKI) and is an effective second-line treatment for patients with advanced-stage non-squamous-cell lung cancer. Previously, only 2 cases of radiation recall after erlotinib treatment have been reported. Here, we report a case of RRP caused by treatment with erlotinib 4 months after palliative definitive hypofractionated radiation therapy (RT).

A 58-year-old male patient with non-small cell lung cancer (adenocarcinoma) was treated with polychemotherapy, palliative RT (30 Gy in 10 fractions), and erlotinib thereafter.

Dosimetric analysis obtained from a 3-dimensional conformal RT planning system revealed that the volume of lung receiving at least 20 Gy (V20) was 21.2% and the mean lung dose was 12.7 Gy. These data indicate that systemic administration of a TKI, even after palliative RT, may lead to unexpected toxicity when the radiation field encompasses visceral organs.

We conclude that the use of a TKI after RT may trigger radiation pneumonitis. Although evidence is limited, we advise clinicians to be cautious of RRP after erlotinib treatment.