In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: We describe the clinical course and pathological findings in a 65 yr - old man with gastric adenocarcinoma who developed renal failure and thrombocytopenia while on treatment with mitomycin C and died in pulmonary edema .
### Output Text:
We describe the clinical course and pathological findings in a 65 yr - old man with gastric adenocarcinoma who developed renal failure and thrombocytopenia while on treatment with <span class="chemical">mitomycin C</span> and died in pulmonary edema . 