Tag Archives: disease

Cancer-Causing Mutations Can Occur By Chance as Millions of Cells Divide

“When the DNA double helix was first revealed by Watson and Crick in 1953, its structure seemed perfect and robust, well-designed to resist most of the disruptive influences that might be present inside living cells. For example, the bases in the double helix are turned inward and thus are not very susceptible to direct attack by chemical mutagens. Moreover, the linkages between adjacent bases were found to be resistant to cleavage by alkaline ions that arise continually in the cell.

“But while the double helix itself is relatively resistant to chemical attack, the process of maintaining a cell’s genetic integrity has a weak link. The vulnerability derives from the need to replicate the cell’s genome each time the cell goes through the process of growth and division. The resulting duplicate copies of the genome enable the mother cell to endow each of its daughters with a genome precisely equivalent to the one that it carries itself.

“This process of DNA replication has flaws. On occasion, a cell will miscopy a sequence of its DNA prior to cell division, and as a consequence, one of its daughters will receive a slightly miscopied genome, in effect a mutated one. Even the best-functioning cells will occasionally miscopy one in a million (or ten million) bases during each cycle of DNA replication. Hence, cell growth and division create vulnerability mutation.

“This imperfection suggested another way cancer formation might be accelerated. Agents that promote cell growth will indirectly create mutations simply because they force cells to replicate their DNA. More DNA copying means more inadvertent copying mistakes, hence more mistakes.”

Evidence Based Medicine and the Aristotelian Approach

“…How do medical myths persist among practicing physicians? Part of the persistence comes from the idea that new studies aren’t really needed. There’s that old Aristotelian pull. The whole idea of empirical testing goes against the Aristotelian approach that has been a guiding principle of research. Under this approach, researchers should first try to understand the nature of the disease. Once you understand the problem, a solution will become self-evident…Instead of focusing on the front-end knowledge about the true nature of disease, [evidence-based medicine] shows the power of asking the back-end question of whether specific treatments work…The Aristotelian approach can go seriously wrong if doctors embrace a mistaken conception or model for how an ailment operates.” (p. 88-89)