title: Effect of Intermittent versus Chronic Calorie Restriction on Tumor Incidence: A Systematic Review and Meta-Analysis of Animal Studies.
abstract: Both chronic calorie restriction (CCR) and intermittent calorie restriction (ICR) have shown anticancer effects. However, the direct evidence comparing ICR to CCR with respect to cancer prevention is controversial and inconclusive. PubMed and Web of Science were searched on November 25, 2015. The relative risk (RR) [95% confidence interval (CI)] was calculated for tumor incidence, and the standardised mean difference (95% CI) was computed for levels of serum insulin-like growth factor-1 (IGF-1), leptin, and adiponectin using a random-effects meta-analysis. Sixteen studies were identified, including 11 using genetically engineered mouse models (908 animals with 38-76 weeks of follow-up) and 5 using chemically induced rat models (379 animals with 7-18 weeks of follow-up). Compared to CCR, ICR decreased tumor incidence in genetically engineered models (RR = 0.57; 95% CI: 0.37, 0.88) but increased the risk in chemically induced models (RR = 1.53, 95% CI: 1.13, 2.06). It appears that ICR decreases IGF-1 and leptin and increases adiponectin in genetically engineered models. Thus, the evidence suggests that ICR exerts greater anticancer effect in genetically engineered mouse models but weaker cancer prevention benefit in chemically induced rat models as compared to CCR. Further studies are warranted to confirm our findings and elucidate the mechanisms responsible for these effects.
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Nantong University, Nantong, Jiangsu, China.|Department of Medical Informatics, School of Medicine, Nantong University, Nantong, Jiangsu, China.
authors.forename: Yalan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Nantong University, Nantong, Jiangsu, China.|Department of Human Resources, Nantong University, Nantong, Jiangsu, China.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Ling
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Nantong University, Nantong, Jiangsu, China.
authors.forename: Guanglei
authors.initials: G
authors.lastname: Su
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Nantong University, Nantong, Jiangsu, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Han
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Nantong University, Nantong, Jiangsu, China.
authors.forename: Xikang
authors.initials: X
authors.lastname: Fan
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health-Bloomington, Indiana University, Bloomington, IN, USA.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Xun
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Nantong University, Nantong, Jiangsu, China.
authors.forename: Guangfei
authors.initials: G
authors.lastname: Xu