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: In all , 12 of 16 kindreds manifesting BRCA1 mutation or linkage contained ovarian cancer , as compared with only 6 of the remaining 31 families ( P < . 001 ) .
### Output Text:
In all , 12 of 16 kindreds manifesting BRCA1 mutation or linkage contained <span class="disease">ovarian cancer</span> , as compared with only 6 of the remaining 31 families ( P < . 001 ) . 