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: However , these mutations are uncommon in the population and they probably account for only a few percent of all breast cancer incidence .
### Output Text:
However , these mutations are uncommon in the population and they probably account for only a few percent of all <span class="disease">breast cancer</span> incidence . 