Scientists looking for new ways to fight cancer may be aiming at the wrong target, research suggests.

The most dangerous cancer cells are not necessarily those that proliferate the fastest, according to a US study.

Instead of focusing on rapidly reproducing cells, scientists may be better off targeting those best able to survive and alter their environment, it is claimed.

Up until now it has generally been assumed that the rapid cell division is the main driving force behind tumour growth.

But this view is based on what has been seen under artificial laboratory conditions, where cancer is often allowed to grow unchecked.

In a patient’s body, growth is restrained by factors such as space, nutrients and oxygen. Rapid proliferation of cancer cells can be offset by higher rates of cell death.

The really successful cancer cells are those that evolve to overcome such restraints, say the researchers.

Such a subgroup of cells is likely to dominate a tumour and spread. But it can also be kept in check by other competing groups of cancer cells.

Professor Kornelia Polyak, from the Dana Farber Cancer Institute in Boston, who tested different subgroups of breast cancer in laboratory mice, said therapies that target fast-proliferating cancer cells could actually be harmful.

By removing a key competitor, such drugs could provide openings for growth-driving strains.

“The goal of precision therapy for cancer is to kill the subsets of cells that are driving the tumour’s growth, even if other subsets are proliferating more robustly,” said Polyak.

“We need to be sure we’re targeting the actual drivers.”

Her research is published in the journal Nature.