SERM is the abbreviation of the selective estrogen receptor modulator which is 
the synthetic ligands of estrogen receptor (ER) acting estrogenically or 
anti-estrogenically among various tissues through modifying the ER function. 
Clomifene, tamoxifen, toremifene and raloxifene are generally classified as SERM 
in the clinical use. The main cause of postmenopausal osteoporosis is estrogen 
deficiency and it was revealed that the continuous combined use of conjugated 
estrogen and medroxyprogesterone acetate reduced the relative risk of femoral 
neck fracture to 0.66, however increased the relative risk of cardiovascular 
event and breast cancer to 1.29 or 1.26, respectively. From the standpoint of 
safe and clinical compliance for the breast and uterine tissue, raloxifene is 
recommendable for middle aged postmenopausal osteoporosis.