What causes cancer - "bad luck" or extrinsic factors?

Earlier this year, a team of researchers at John Hopkins University published a paper which suggested that random mutations in DNA had a significant role to play in cancer development. These findings were popularly interpreted to mean that “bad luck,” more than any other causative factor, leads to cancer. This has sparked a debate among the experts in the field. Now, Yusuf Hannun of Stony Brook University in New York and his team has published a study that attempts to refute the claim that cancer is a result of random cell division. According to this study, which involved computer modeling, population data and genetic approaches, only 10-30% of cancer cases are a result of random mutations. The major cancer-causing reasons are extrinsic, such as toxic chemicals, radiation, and other lifestyle-related factors. Hannun, however, agrees that “There is still an element of luck,” when it comes to cancer as both intrinsic and extrinsic factors play a combined role.

Read more in The Scientist.