The International Agency for Research on Cancer (IARC) has said it “strongly disagrees” with the conclusion of a scientific report on the causes of human cancer published in the journal Science on 2 January 2015.
The World Health Organisation’s specialised cancer agency said the study, which has received widespread media coverage, compares the number of lifetime stem cell divisions across a wide range of tissues with lifetime cancer risk and suggests that random mutations (or “bad luck”) are “the major contributors to cancer overall, often more important than either hereditary or external environmental factors.”
IARC says there are “limitations and biases in the analysis” and a “serious contradiction” between the paper’s conclusion and the extensive body of scientific evidence on the issue. “We already knew that for an individual to develop a certain cancer there is an element of chance, yet this has little to say about the level of cancer risk in a population,” explains IARC director Dr Christopher Wild.
“Concluding that ‘bad luck’ is the major cause of cancer would be misleading and may detract from efforts to identify the causes of the disease and effectively prevent it.” Noting that preventive efforts and not luck had led to substantial reductions in some cancers, the IARC director concludes: “The remaining knowledge gaps on cancer aetiology should not be simply ascribed to ‘bad luck’. The search for causes must continue while also investing in prevention measures for those cancers where risk factors are known.”