Variations on a theme that implicates apolipoprotein E (APOE), a gene related to the risk of Alzheimer’s disease, are present in the literature pertaining to cancer related cognitive impairment (CRCI) in breast cancer patients.55 Unfortunately, the literature is at odds as to whether APOE genotype is meaningful in predicting risk of CRCI. This evidence concerns the gene APOE and early-onset autosomal dominant Alzheimer disease.