Trastuzumab-Induced Organising Pneumonia in Breast Cancer Patient

Abstract

Patients with metastatic breast cancer often have respiratory symptoms due to various causes. Trastuzumab is a drug used in the treatment of HER2/neu over-expressing breast cancer patients. Organising pneumonia is a type of idiopathic interstitial pneumonia that mimics infection or progressive disease and can be difficult to diagnose in the setting of malignancy. Making a correct diagnosis is of extreme importance since any delay in the treatment can result in significant adverse patient outcome. Here, we have described a case of organising pneumonia associated with the use of trastuzumab in metastatic breast cancer patients. On the basis of clinical data, including findings such as a decreased PaO2 level and findings on chest CT scan, these patients were diagnosed with drug-induced organising pneumonia. Although it is a rare adverse event associated with trastuzumab, it may cause rapid deterioration without preceding symptoms; hence, even though it is very rare, with an incidence of less than 2%, it is still crucial to intervene so as to prevent the occurrence of such an unfavourable outcome by means of close observation and early diagnosis along with an early withdrawal of the drug and an immediate commencement of corticosteroid therapy.