Current law in the 'Workers' Compensation Act of Colorado' provides that certain cancers contracted by firefighters are considered occupational diseases presumed to have been a result of the firefighters' employment. A firefighter's employer or an insurer may rebut this presumption by showing by a preponderance of the medical evidence that the cancer did not occur on the job.      Section 2 of the bill updates the law by:Expanding the types of cancer that are considered occupational diseases;Affording certain neurological conditions the presumption; andStrengthening the presumption to require an employer to show clear and convincing evidence that the cancer or neurological condition did not occur on the job.      The bill exempts firefighters who are employed by the state.(Note: Italicized words indicate new material added to the original summary; dashes through words indicate deletions from the original summary.)(Note: This summary applies to the reengrossed version of this bill as introduced in the second house.)