PGR and breast cancer: Contrarily, a French study reported an increase of breast cancer risk with the Western diet for ER+/positive progesterone receptor (PR+) tumors (HR 1.20, 95% CI: 1.03-1.38), and a negative association of the MD for breast cancer risk (HR 0.85, 95% CI: 0.75-0.95), especially for ER+/PR- tumors [27].