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: RESULTS Four missense mutations producing amino acid substitutions and a somatic 12 - base pair deletion in the coding region of the DPC4 gene were detected in the 31 cancers ( 16 % ; 5 of 31 ) .
### Output Text:
RESULTS Four missense mutations producing amino acid substitutions and a somatic 12 - base pair deletion in the coding region of the DPC4 gene were detected in the 31 <span class="disease">cancers</span> ( 16 % ; 5 of 31 ) . 