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

### Input Text: Twenty - three families were identified through two high - risk breast cancer research programs .
### Output Text:
Twenty - three families were identified through two high - risk <span class="disease">breast cancer</span> research programs . 