CYP19A1 and osteoporosis: On the other hand, a meta-analysis revealed that all aromatase inhibitors had a higher incidence of osteoporosis compared to tamoxifen, but that the incidence of osteoporosis was lower in patients using exemestane than in those using anastrozole (OR: 0.8594, 95% CI: 0.5766-1.168) and letrozole (OR: 0.7358, 95% CI: 0.4301-1.307) (21).