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: We have conducted a large - scale population study to investigate the prevalence of specific BRCA1 and BRCA2 mutations in Ashkenazi Jewish individuals who were unselected for breast cancer .
### Output Text:
We have conducted a large - scale population study to investigate the prevalence of specific BRCA1 and BRCA2 mutations in Ashkenazi Jewish individuals who were unselected for <span class="disease">breast cancer</span> . 