It all adds up
Individual cancer-causing mutations have a minute effect on tumor growth, increasing the rate of cell division by just 0.4 percent on average, according to new mathematical modeling by scientists at Harvard University, Johns Hopkins University, and other institutions. The research, appearing this week in the Proceedings of the National Academy of Sciences (PNAS), reinforces that cancer is the culmination of many accumulated mutations. It also highlights the fundamental heterogeneity and randomness of many cancers, consistent with the observations of epidemiologists and clinicians. “This work suggests that significant tumor growth probably requires the slow and steady accumulation of multiple mutations in a cell over a number of years,” says lead author Ivana Božić, a doctoral student in Harvard’s Department of Mathematics and Program for Evolutionary Dynamics. “It also helps explain why so many cancer-driving mutations are needed to form an advanced malignancy within the lifetime of an individual.” All cells undergo regular division and...