Researchers have demonstrated "in theory" that a protein antigen from a childhood vaccine can be delivered into the cells of a malignant tumour to refocus the body's immune system against the cancer, effectively halting it and preventing its recurrence.

The bacteria-based intracellular delivering (ID) system uses a non-toxic form of Salmonella that releases a drug, in this case a vaccine antigen, after it's inside a solid-tumour cancer cell.