New tumour theory could change cancer treatment

University of Sydney researcher Dr Guy Lyons has come up with a new theory of cancer tumours that could change the way we treat cancer and conduct research into its causes.

While most approaches to malignant tumours treat them as homogeneous, Dr Lyons's research, which has just won a prestigious award at an international cancer congress, suggests tumours might be composed of two or more interacting populations of cells.

Dr Lyons said: "Cancer is caused by mutations in genes that control cell growth. In our theory, distinct mutations occur in different cells within the cancer cell population. These cells then cooperate to form a malignant tumour."

Currently, malignant tumours are treated as homogeneous. "When a laboratory looks for a set of mutations in a tumour for diagnostic or research purposes, the first thing that is done is to homogenise a sample of that tumour, and then the homogenate is analysed for mutations.

"If the tumours are mixtures of cells with distinct mutations, then the picture obtained from the homogenate will be an 'average' one, but not accurate for any one cell within the tumour.

"By assuming that every cancer cell in a tumour has all of the mutations that caused the tumour, errors could be made in treating patients. Therapies designed to kill cancer cells that have two particular mutations will not work if the mutations are present in separate cells within the tumour. This will become important as personalised cancer care based on genetic analyses of tumours becomes more common."

Dr Lyons' research creates opportunities to design novel treatments for cancer. Therapies that interfere with the molecules used by cancer cells to cooperate might be developed.

Researchers at the University's Dermatology Research Laboratories and the Sydney Head and Neck Cancer Institute are conducting experiments to determine how often tumours of the skin and head and neck regions use cancer cell cooperation to become malignant, and which sorts of mutations are involved in the cooperative behaviour.

"By simulating cancers using a computer program, we will be able to identify the optimal targets for developing new therapies," says Dr Lyons.

Dr Lyons' work was awarded Best Science Paper at the 2009 International Academy of Oral Oncology World Congress in Toronto, recognising the work he has done with Dr Mary Myerscough, Senior Lecturer at the University of Sydney's School of Mathematics, and their PhD student, Mr Erwin Lobo.

Dr Guy Lyons is Clinical Senior Lecturer, Dermatology, at the University of Sydney. He is also a member of the University of Sydney Cancer Research Network.