Cancer Protection Elicited by a Single Nucleotide Polymorphism Close to the Adrenomedullin Gene

Context: The risk of developing cancer is regulated by genetic variants, including polymorphisms. Characterizing such variants may help in developing protocols for personalized medicine. Objective: Adrenomedullin is a regulatory peptide involved in cancer promotion and progression. Carriers of a single nucleotide polymorphism (SNP) in the proximity of the adrenomedullin gene have lower levels of circulating peptide. The aim of the present work was to investigate whether carriers of this SNP (rs4910118) are protected against cancer. Design: This was a retrospective study. DNA samples were obtained from the Carlos III DNA National Bank (University of Salamanca, Salamanca, Spain). Setting: Samples represent a variety of donors and patients from Spain. Patients or Other Participants: DNA from patients with breast cancer (n = 238), patients with lung cancer (n = 348), patients with cardiac insufficiency (n = 474), and healthy donors of advanced age (n = 500) was used. Interventions: All samples were genotyped using double-mismatch PCR, and confirmation was achieved by direct sequencing. Main Outcome Measures: The minor allele frequency was calculated in all groups. The Pearson χ2 was used to compare SNP frequencies. Results: Of 1560 samples, 14 had the minor allele, with a minor allele frequency in healthy donors of 0.90%. Patients with cancer had a statistically significantly lower frequency than healthy donors (odds ratio = 0.216, 95% confidence interval = 0.048–0.967, P = .028). Conclusions: Carriers of the minor allele have a 4.6-fold lower risk of developing cancer than homozygotes for the major allele. Knowledge of the rs4910118 genotype may be useful for stratifying patients in clinical trials and for designing prevention strategies.