CD4 and neoplasm: The immune system is susceptible to age‐related changes especially in the CD4 compartment with an expansion of CD4 Tregs with age.45 Telomere length and telomerase activity also have effects on the immune system with the expansion of CD4+ and CD25+ regulatory T cells with shorter telomeres.46 A second hypothesis is that the beneficial effect of nevus number on survival may reflect a modifying effect on tumor cell telomeres.