The ability of an organ's stem cells to generate new tissue over time — the cells' generative capacity — determines how prone that organ is to cancer.

Scientists have debated the relative importance of factors that contribute to an organ's cancer risk, including 'intrinsic' factors such as the number of stem-cell divisions and 'extrinsic' factors that cause tissue and DNA damage. To compare these factors, Richard Gilbertson at the CRUK Cambridge Institute, UK, Arzu Onar-Thomas at St Jude Children's Research Hospital in Memphis, Tennessee, and their colleagues studied stem cells called Prom1+ cells with varying levels of generative capacity in different organs in mice of various ages. The authors introduced key cancer-causing mutations into the cells, then looked for tumour growth in the organs.

The team found that cancer risk correlated closely with the generative capacity of the Prom1+ cells. In liver tissue, cancer mutations alone did not cause cancer — tissue injury significantly increased cancer susceptibility. The authors propose that several factors contribute to a 'perfect storm' of tumour growth: mutated stem cells and extrinsic factors that trigger cell proliferation.

Cell http://doi.org/bp73 (2016)