LEP and breast cancer: No significant association between leptin values and breast cancer risk was observed considering neither values measured with the ELLA method (HR = 1.32; 95% CI: 0.46;3.77, highest quartile versus lower quartiles, p = 0.60, Figure 4C), nor with the ELISA method (HR = 1.29; 95% CI: 0.45;3.69, p = 0.64, Figure 4D).