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: However , long - term survival is possible when radical cystectomy is performed for bladder tumors with any sign of invasion and for recurrent high grade disease , even when noninvasive .
### Output Text:
However , long - term survival is possible when radical cystectomy is performed for bladder tumors with any sign of invasion and for recurrent high grade disease , even when noninvasive . 