Basal-cell carcinoma
Basal-cell cancer is a very common skin cancer. It is much more common in fair-skinned individuals with a family history of basal-cell cancer and increases in incidence closer to the equator or at higher altitude. There are approximately 800,000 new cases yearly in the United States alone. Up to 30% of Caucasians develop basal-cell carcinomas in their lifetime. In Canada, the most common skin cancer is basal-cell carcinoma (as much as one third of all cancer diagnoses), affecting 1 in 7 individuals over a lifetime.
Stem-cell niche
Stem cell niches harboring continuously dividing cells, such as those located at the base of the intestinal gland, are maintained at small population size. This presents a challenge to the maintenance of multicellular tissues, as small populations of asexually dividing individuals will accumulate deleterious mutations through genetic drift and succumb to mutational meltdown. Mathematical modeling of the intestinal gland reveals that the small population size within the stem cell niche minimizes the probability of carcinogenesis occurring anywhere, at the expense of gradually accumulated deleterious mutations throughout organismal lifetime—a process that contributes to tissue degradation and aging. Therefore, the population size of the stem cell niche represents an evolutionary trade-off between the probability of cancer formation and the rate of aging.