Tamoxifen hypercalcemia with

Tamoxifen can be used in both premenopausal and postmenopausal women with metastatic breast cancer who have tumors that are hormone-receptor-positive. The toxicities of tamoxifen are described in the section on adjuvant endocrine therapy. The only additional toxicity that one might expect to find in the setting of metastatic breast cancer (specifically bone metastases) is a tumor flare or hypercalcemia, which occurs in approximately 5% of patients following the initiation of any SERM therapy and is not an indication to discontinue SERM therapy. It is generally accepted that this is a positive indication that the patient will respond to endocrine therapy. 

Tamoxifen is the antiestrogen of choice in premenopausal women whose tumors are hormone-receptor positive, unless metastases occur within 1 year of adjuvant tamoxifen. Maximal beneficial effects do not occur for at least 2 months. In addition to the side effects described for adjuvant therapy, tumor flare or hypercalcemia occurs in approximately 5% of patients with MBC. 

Tamoxifen administration is associated with few toxic side effects, most frequently hot flashes (in 10-20% of patients) and occasionally vaginal dryness or discharge. Mild nausea, exacerbation of bone pain, and hypercalcemia may occur. 

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