Is tamoxifen a must for er/pr negative menstruating woman for breast cancer treatment?

No: Actually, it's er/pr positive women who are potential candidates for tamoxifen. This is advised for women whose cancer stage mandates chemotherapy, sometimes combined with traditional IV chemotherapy. Furthermore, we often recommend tamoxifen to prevent the development of a second cancer is breast cancer survivors.

No: This and similar medicines are anti Estrogens that block the receptors. So if the patient has negative receptors there is little benefit from the medication. So it's not a must.