REDucing Hot FLASHes in Women Using Endocrine Therapy.

Inclusion Criteria:

• Pre-, peri- or postmenopausal women of 18 years or above;

• Indication for endocrine therapy and already started with tamoxifen, aromataseinhibitors or luteinizing hormone-releasing hormone analogues for at least 4 weeksand planning to continue for the duration of the study;

• Experiencing hot flashes with a minimum of 14 per week for at least 1 month anddesire to start a pharmacologic intervention.

Exclusion Criteria:

• Pregnant;

• Breast feeding;

• Patients who receive chemotherapy or immunotherapy/HER2 antibodies within the prior 8 weeks, and patients scheduled for chemotherapy during the study period;

• Palliative setting;

• Use of venlafaxine or any other antidepressants, also including St. John's wortwithin the previous year;

• Creatinine clearance < 30 ml/min;

• Liver cirrhosis;

• Use of gabapentin and/or calcium channel antagonists within 2 weeks of study entry;

• Use of oxybutynin before study entry;

• Use of any other substances or therapies for the treatment of hot flashes, forinstance acupuncture.