Several cancer patients received leaflets that warned them about their treatment being at a risk under the Conservatives and David Cameron blasted Labour tactics as sick after this happened.
Patients stated that the leaflets were appalling.
The problem began following Labour sending leaflets stating that Tories would axe the guarantee to see a specialist within two weeks for cancer patients.
People suffering from cancer stated that they got a leaflet while their friends or neighbors without the disease did not get it.
Nottingham-based Phyllis Delik, 80, stated that it was callous to send her the leaflet.
Cameron said, "This is an absolutely appalling way to behave. If Gordon Brown has a moral compass he should have a good look at it and apologize to these people."
Shadow health secretary Andrew Lansley asked Brown whether Labour used confidential information to target cancer patients.
According to Labour 250,000, people were sent the cancer-care card.