ESR1 and breast cancer: Although the difference in overall effect sizes for different breast cancer subtypes were less impressive in the validation dataset, the strongest protective effect was similarly observed for the ER-negative subtype (OR> 5 cups/day: ≤ 1 cup/day: 0.67 (0.43, 1.05), P trend = 0.326), followed by the PR-negative subtype (OR> 5 cups/day: ≤ 1 cup/day: 0.70 (0.49, 1.00), P trend = 0.280).