Why are some cells more cancer prone?

In many organs, like the small intestine, adult stem cells play a vital role in maintaining function by replacing old cells with new ones.

http://www.sciencedaily.com/releases/2013/08/130827160516.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily%2Fhealth_medicine%2Fcancer+%28ScienceDaily%3A+Health+%26+Medicine+News+--+Cancer%29