Researchers: Cancer often due to biological ‘bad luck’

(Bloomberg) — In a majority of the cases, cancer may be the result of biological bad luck rather than caused by genes or environmental factors, with the random division of stem cells making people more vulnerable to mutations, a new study shows.

A formula that plotted the number of stem-cell divisions over a lifetime against the risk of cancer showed a correlation and explained two-thirds of cases, according to a research paper published this week in the journal Science. The study, conducted by mathematician Cristian Tomasetti and geneticist Bert Vogelstein of Johns Hopkins University, hinges on previously published cancer statistics.

The research may bolster arguments that cancer often can’t be prevented, with risky behavior such as smoking and excessive exposure to the sun being less of a factor than chance. That would support focusing more resources on diagnosing the disease in early stages and on treatments to reduce mortality rates.

The researchers cautioned that the study isn’t a license to engage in unhealthy behavior. “Cancer-free longevity in people exposed to cancer-causing agents, such as tobacco, is often attributed to their ’good genes,’ but the truth is that most of them simply had good luck,” Vogelstein said in a statement.

See also: Aspirin tied to reduced risk of liver cancer.

Tissue types that have more stem-cell divisions are more prone to mutations that can lead to cancers, with data demonstrating a statistical correlation between the two, Vogelstein and Tomasetti said in their paper. They suggest that only one-third of the variation in cancer risk may be due to environmental factors or inherited predispositions.