Bleomycin's major pulmonary toxicity?

• A. Pulmonary fibrosis or interstitial pneumonitis
• B. Cardiotoxicity
• C. Hepatotoxicity
• D. Nephrotoxicity

Answer: (A)

Bleomycin is most notable for causing a dose‑related lung injury, specifically interstitial pneumonitis that can progress to pulmonary fibrosis. This happens because the lungs have relatively low levels of bleomycin hydrolase, an enzyme that inactivates the drug, so bleomycin can accumulate there and trigger oxidative damage to alveolar cells and the interstitium. The injury tends to be lung‑specific rather than affecting the heart, liver, or kidneys as a primary toxicity, which is why pulmonary toxicity is the hallmark concern. Clinically, patients develop a dry cough and progressive shortness of breath, with basilar crackles and restrictive changes on testing; imaging often shows basilar, diffuse interstitial infiltrates. Risk factors include a high cumulative dose, older age, prior chest irradiation, and the need for supplemental oxygen, which can worsen injury. Management centers on stopping bleomycin, avoiding unnecessary oxygen exposure, and treating inflammatory stages with steroids if indicated.