The most serious long-term side effect of bleomycin therapy is which of the following?

a. Pulmonary fibrosis

While any chemotherapeutic drug may exhibit a diverse array of toxicities, most classes of drugs are known for particular adverse effects. These are often graded by their severity from 0 (no toxicity) through 4 (life-threatening toxicity); grade 5 toxicity is equivalent to death. Most therapies allow for dosage reductions for toxicities greater than grade 2 or 3; one exception is the therapy of acute leukemia, where a grade 4 hematologic toxicity is expected. Some toxicities are only observed with prolonged drug administration, such as anthracycline-induced cardiotoxicity, bleomycin-and nitrosourearelated pulmonary fibrosis, or secondary leukemias associated with the nitrosoureas, etoposide, or mechlorethamine (nitrogen mustard), or when drugs are given at very high doses (nitrosourea-related hepatic veno-occlusive disease), or are given regionally (chemical peritonitis, arteritis, or biliary sclerosis).