Causality and Chance in the Development of Cancer

In addition to heredity and the environment, chance may also play a role in the development of cancer. Because the acquisition of mutations is stochastic with each cell division, organs with more stem-cell replication seem to develop cancer more often. The notion that, in addition to heredity (HER) and the environment (ENV), chance (C) is also a factor in oncogenesis is not new. 1 , 2 However, it has received new impetus from the recent work by Tomasetti and Vogelstein, 3 who reported a strong correlation between the frequency of tumors of individual organs or tissue types and the estimated number of stem-cell divisions in those organs or tissues. Thus, the wide variation between common tumors (e.g., colorectal cancer, which will develop in nearly 1 in 20 persons) and very rare tumors (e.g., osteosarcoma, which will develop in fewer than 1 in 10,000 . . .