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: Many efficacious cancer treatments cause significant cardiac morbidity , yet biomarkers or functional indices of early damage , which would allow monitoring and intervention , are lacking .
### Output Text:
Many efficacious cancer treatments cause significant cardiac morbidity , yet biomarkers or functional indices of early damage , which would allow monitoring and intervention , are lacking . 