The study was done in women in France. From the abstract:
Methods: 65,574 women from the Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l’Education Nationale (E3N) cohort were followed from 1993 to 2014. Incident BC cases were identified and validated. The PD [paleolithic diet] score was calculated using dietary intake self-reported at baseline (1993) and follow-up (2005) or baseline only if censored before follow-up. Multivariable Cox proportional hazards regression models were used to estimate BC hazard ratios (HR) and 95% confidence intervals (CI).Results: Over a mean follow-up of 20 years, 3968 incident BC cases occurred. An increase of 1 standard deviation in the PD score was associated with an 8% lower BC risk, fully-adjusted model: HR1-SD 0.92, 95% CI; 0.89, 0.95. Compared to women with low adherence to the PD, women with high adherence had a 17% lower BC risk, HRQ5 vs Q1 0.83, 95% CI; 0.75, 0.92, Ptrend < 0.01. When considering BC [breast cancer] subtypes, we observed the same pattern of association (Pheterogeneity > 0.10 for all).Conclusions: High adherence to a PD characterised by fruit, vegetables, nuts, fish, and lean meat and limited in dairy, grains, legumes, refined sugar, and alcohol was associated with a lower BC [breast cancer] risk. The lack of heterogeneity according to BC subtypes could indicate the involvement of non-hormonal mechanisms.
Steve Parker, M.D.
Paleo Diabetic 