Researchers presented evidence for the existence of cancer stem cells, with three different studies seeking to end a decades-old scientific dispute about how tumours grow.

The discovery should lead to new drugs, targeting stem cells that cause tumours to reappear after cancer therapy, the teams argued in three scientific papers published simultaneously in the journals Nature and Science.

“The hypothesis (that cancer stem cells exist) has been around now for some time. Hopefully, these three papers now make an end to the discussion,” Dutch researcher Hugo Snippert said.

All the studies were conducted on lab mice.

Some experts have maintained that tumours are comprised of masses of cancer cells that are all the same, and all dividing.

But Mr Snippert said the latest papers clearly show a hierarchy of cells in tumours, with different functions – including stem cells that act as cancer cell factories.

Stem cells are infant cells that develop into specialised tissues of the body, touted by medicine as a future source from which to replenish damaged tissue.

Cancer stem cells must now be targeted for drug research, argued Mr Snippert, a member of the University Medical Centre Utrecht research team which focused on intestinal cancer and published its findings in Science.

“Since the cancer stem cells are so similar to normal stem cells, most treatments also harm the normal stem cells,” he said.