In general terms, any individual who can prove that he (or she) has 'a physical or mental impairment which has a substantial and long-term adverse effect' on their ability to carry out day-to-day activities is protected under the anti-discrimination provisions of the Disability Discrimination Act (DDA). An individual with a progressive condition would be covered - even if there was currently no substantial adverse effect, or the condition was in remission - if it had produced an impairment which had some adverse effect on their current ability to carry out day-to-day activities, and was likely to lead to a substantial adverse effect over time. It can also cover impairments that 'go away', but are likely to recur, for example, a knee or back problem.
That definition would cover many forms of cancer. However, for the removal of any uncertainty, the definition of disability under the Act specifically includes most cancers, multiple sclerosis and HIV-Aids, as well as a wider range of mental illnesses.
The Employment Appeals Tribunal has ruled that employers can apply their sick pay policy to disabled employees who are absent because of their disability. So if, for instance, you normally cut back on the wages of people who are absent because of long-term sickness after a given period, you can do the same with people who are disabled, even though their absence arises because of their disability.
The House of Lords has upheld this approach, saying that the test of whether there has been disability discrimination is whether a non-disabled person would have been treated the same way if he had done (or not done) what the disabled person did (or did not) do. It is irrelevant whether the act or omission was because of the person's disability.
The net result is to make it easier for you to take on people who are disabled, though tougher for them if they have to take time off because of their disability. Your best course is to base your decision on whether or not to shortlist on written, objective criteria, and to keep a record of how those criteria applied to all the candidates.
