Basal-cell carcinoma
In the United States approximately 3 out of 10 caucasians develop a basal-cell carcinoma during their lifetime. This tumor accounts for approximately 70% of non-melanoma skin cancers. In 80 percent of all cases, basal-cell carcinoma affects the skin of head and neck. Furthermore, there appears to be an increase in the incidence of basal-cell cancer of the trunk in recent years.
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.