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Cyclophosphamide pulmonary toxicity

Ulrich Specks, MD
Section Editors
Kevin R Flaherty, MD, MS
James R Jett, MD
Deputy Editors
Helen Hollingsworth, MD
Diane MF Savarese, MD


Cyclophosphamide is an alkylating agent that is used in combination with other chemotherapeutic agents for the treatment of a variety of malignant processes. It also has immunosuppressive properties and is increasingly used for the treatment of certain autoimmune diseases, either as a sole agent or in combination with glucocorticoids. Long-term use of cyclophosphamide is associated with a multitude of significant side effects, such as hair loss, leukopenia, hemorrhagic cystitis, infertility, the development of secondary malignancies, and pulmonary toxicity.

The pathogenesis, clinical manifestations, diagnosis, and treatment of cyclophosphamide pulmonary toxicity will be presented here. Other toxicities of cyclophosphamide are discussed separately. (See "General toxicity of cyclophosphamide in rheumatic diseases" and "General principles of the use of cyclophosphamide in rheumatic diseases" and "Cystitis in patients with cancer" and "Ovarian failure due to anticancer drugs and radiation" and "Effects of cytotoxic agents on gonadal function in adult men".)


Histopathologic findings observed in patients with cyclophosphamide pulmonary toxicity are nonspecific. The characteristic picture is the presence of atypical cells in the alveolar and bronchiolar epithelium, hyperplasia of type II pneumocytes, and interstitial and alveolar edema and fibrosis [1]. Diffuse alveolar damage, organizing pneumonia (also known as bronchiolitis obliterans organizing pneumonia or BOOP), and alveolar hemorrhage have been reported [2], and a pattern indistinguishable from usual interstitial pneumonitis (UIP) also can be seen [3]. (See "Role of lung biopsy in the diagnosis of interstitial lung disease".)

Among patients with late onset pulmonary toxicity, a pattern of pleuropulmonary fibrosis or fibroelastosis can be seen, affecting the upper and lateral aspects of the pleura [4-7].


The parent drug cyclophosphamide is nontoxic to the lung but it is metabolized in the liver, and to a lesser extent in the lung, to the toxic metabolites 4-hydroxycyclophosphamide, acrolein, and phosphoramide mustard [8]. Lung tissue from different species varies in its ability to locally metabolize cyclophosphamide, and susceptibility to cyclophosphamide-induced lung fibrosis in humans may depend upon genetic differences in local pulmonary drug metabolism [9]. Genetic susceptibility is further supported by the absence of a clear dose-response relationship for the development of lung toxicity in humans [3,10].

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Literature review current through: Nov 2017. | This topic last updated: Jul 11, 2017.
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