Question

Genetic mutation is what leads to the mechanism of natural selection, and thus contributes directly to evolution, a necessary and useful process. The crossing over and randomization at fertilization also increases variation. Without the variation that results from mutations, natural selection would not occur, thus proving that genetic mutations are beneficial and crucial for life. However, cancer is a disease caused by mutation. Does this mean that cancer is inescapable for all humans if we simply live long enough?  

Answer 1

Natural selection is a selection pressure which operates in a population and allow the best fitted genotype to survive in changing environmental conditions and eliminate the other genotype which are not fit. Mutation is one of the main cause of natural selection because it results into change in allelic frequency, which is directly linked to evolution, which is nothing but the adaptability of species through a period of time for surviving changing environmental conditions.

Mutation is also one of the reason why cancer occurs, mutation occurs in somatic cells as a result there is uncontrolled cell division, cell growth and no cell death. Mutant form of gene in cancer is called oncogene and normal form of gene is proto-oncogene. Gain of functional mutation in only one copy of alleles results in conversion of proto-oncogene into oncogene which is dominant in nature as a result results in development of cancer (normal proto-oncogenes are recessive in nature). In case of tumor, loss of functional mutation in both copies of alleles are generally recessive in nature that leads to development of tumor (because normal tumor suppressor genes are dominant in nature).

So, it can be considered that cancer is inescapable as well as inevitable for all humans if we simply live long enough.