Acceleration of interstitial lung disease induced by raltitrexed.

Raltitrexed is a folate analogue, which selectively inhibits thymidylate synthase, used in the treatment of colorectal carcinoma. Common side effects include asthenia and gastrointestinal and haematological toxicities. We present the case of a 74-year-old gentleman with incidental mild interstitial lung disease on preoperative staging CT Chest who developed acute breathlessness whilst undergoing adjuvant raltitrexed treatment for a completely excised colorectal adenocarcinoma. Discontinuation of raltitrexed and a course of steroid therapy resulted in resolution of symptoms, mirrored by an improvement in lung function tests. The clinical pattern of rapid progression with steroid response highlights the potential for significant acceleration of interstitial lung disease by raltitrexed.