Robson has had successful operations for colon cancer and a malignant melanoma on his face.

CNN: Sir Bobby Robson taken to hospital

Many scientists believe that the body's own defences against foreign intruders can be harnessed to battle malignant melanoma.

BBC: Supercharged cells fired at skin cancer

Malignant melanoma is the least common, but most aggressive form of skin cancer.

BBC: Twins offer skin cancer clue

Justine Sheils, a 37-year-old administrator from Liverpool, began using sunbeds when she was 15 and was diagnosed with malignant melanoma five years ago.

BBC: Charity demands child sunbed ban

It is not yet known if the chemicals will also help tackle malignant melanoma, the least common but most deadly type of skin cancer.

BBC: Tea lotion could stop skin cancer

He beat bowel cancer in 1992, a malignant melanoma in 1995 and a tumour in his right lung and a brain tumour, both in 2006.

BBC: Legend Sir Bobby Robson, 76, dies

Dr. Katz, who was recently diagnosed with malignant melanoma, says he wouldn't mind retiring "sooner rather than later, " partly due to the uncertainty about his health.

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