Table 2.

Intermittent caloric restriction and cancer incidence: Rodent experiments

Cancer siteaRisk assessmentbAmplitudecFrequencyDurationRef.d
Mammary, DMBA-induced, ratRR = 1.20; 95% CI: 0.68–2.11, NS25% CR1 cycle4 wk CR; 12 wk AL(40)
RR = 0.90; 95% CI: 0.47–1.73, NS25% CR1 cycle4 wk AL, 8 wk CR, 4 wk AL
Mammary, DMBA-induced, ratRR = 0.74; 95% CI: 0.49–1.12, NS50% CR1 cycle5 wk AL, 4 wk CR, 12 wk AL(41)
Mammary, DMBA-induced, ratRR = 0.50; 95% CI: 0.14–1.84, NS50% CR4 cyclesLoss of 20% body weight and then regained(43)
Mammary, DMBA-induced, ratRR = 0.89; 95% CI: 0.59–1.35, NS40% CR15 cycles48 h AL, 48 h CR for 9 wk(44)
Mammary, DMBA-induced, ratRR = 0.90; 95% CI: 0.63–1.30, NS40% CR16 cycles48 h AL, 48 h CR for 10 wk(45)
Mammary, MNU-induced, ratRR = 1.22; 95% CI: 0.89–1.68, NS33% CR4 cycles1 wk CR, 3 wk AL(46)
Mammary, MMTV-TGF-α (lepob/+) transgenic mouseRR = 0.04; 95% CI: 0.01–0.30, P < 0.0550% CR12 cycles3 wk CR, 3 wk, AL(13)
Mammary, MMTV-TGF-α/Lepr+Leprdb transgenic mouseRR = 0.18; 95% CI: 0.09–0.40, P < 0.00150% CR12 cycles3 wk CR, 3 wk, AL(14)
Mammary, MMTV-TGF-α transgenic mouseRR = 0.13; 95% CI: 0.06–0.28, P < 0.0550% CR12 cycles3 wk CR, 3 wk, AL(15)
Mammary, MMTV-Neu transgenic mouseRR = 0.60; 95% CI: 0.27–1.33, NS50% CR12 cycles3 wk CR, 3 wk, AL(18)
Multiple tumor types, p53-deficient (p53+/−) mouseRR = 0.64; 95% CI: 0.31–1.32, NS24-hour fast28–40 cycles1 d/wk for 7–10 mo(20)
Mammary, spontaneous in DBA inbred miceRR = 1.12; 95% CI: 0.94–1.34, NS24-hour fast220 cycles24-hour fast, 2 times/wk for 110 wk(54)

Abbreviations: CR, caloric restriction; AL, ad libitum; NS, not significant; MNU, 1-methyl-1-nitrosourea. DBA refers to a specific inbred mouse strain.

  • aInformation is provided on the cancer site, agent used to induce cancer, and the rodent species used.

  • bThe experimental approaches and number of rodents per treatment group varied markedly among the reported experiments. To provide a more uniform format in which to view and interpret experimental findings, risk assessment was limited to cancer incidence, and RR estimates were calculated using the cancer incidence and N for each group. Ad libitum–fed rodents were used as the referent group, and intermittently calorically restricted rodents were used as the experimental group. RR and CIs for the RR were calculated using the method described in ref. 56.

  • cClassification of weight cycling as defined in ref. 12.

  • dTwo studies discussed in the text are not included in the Table (refs. 16, 17) because final aggregated cancer incidence data could not be accurately ascertained from the reported data. Similarly, refs. 21, 55 are not included because the primary endpoint of these prostate (LAPC-4 cells) xenograft studies was survival; the effect of intermittent caloric restriction was not statistically significant in either study.