The purpose of this study is to determine the effect of toremifene treatment to the MRI findings of the breast in women suffering from premenstrual mastalgia.

Benign breast pain is a common complaint of women in western countries. As many as 41-69% of women reported having mastalgia sufficient to interfere with their daily routines. Approximately 8-10% of premenopausal women suffer monthly from moderate to severe breast pain.Tamoxifen has previously been found to be effective in reducing premenstrual mastalgia. We showed that another triphenylethylene derivative, toremifene, significantly alleviated cyclical breast pain as compared to placebo. In this study women suffering from cyclical breast pain are randomly allocated to receive toremifene (20mg) or placebo during the luteal phase for three consecutive cycles. The patients are then crossed over after a wash-out period to placebo or toremifene, respectively. The MRI investigations are made at two occasions during the premenstrual period after three cycles of toremifene and after three cycles of placebo.

Inclusion Criteria:

• Premenstrual mastalgia
• Age 20-45 years
• Reliable non-hormonal contraception

Exclusion Criteria:

• Pregnancy
• Breast cancer or uterine corpus cancer
• Unexplained menstrual disorders
• Serious health problems
• Hormonal contraception, including hormonal IUD trade name Mirena
• Oestrogen and/or progestin treatment
• Hysterectomy and/or oophorectomy or radiation therapy
• Artificial cardiac pacemaker/metallic prostheses