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: A total of 12 patients with a recurrence of a glioblastoma multiforme underwent re - resection and received an intracavitary application of paclitaxel and carboplatin cubic phases in different dosages .
### Output Text:
A total of 12 patients with a recurrence of a glioblastoma multiforme underwent re - resection and received an intracavitary application of <span class="chemical">paclitaxel</span> and <span class="chemical">carboplatin</span> cubic phases in different dosages . 