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: The occurrence of a myocardial infarction is reported after chemotherapy containing etoposide , in a man with no risk factors for coronary heart disease .
### Output Text:
The occurrence of a myocardial infarction is reported after chemotherapy containing <span class="chemical">etoposide</span> , in a man with no risk factors for coronary heart disease . 