hi read this tamoxifen works by blocking estrogen from attaching to estrogen receptors on these cells. by blocking the estrogen receptors it is believed that the growth of the breast cancer cells will be halted. estrogen is important for your periods. ask your doctor for a blood test for your hormones get your estrogen levels if these have stopped could be your answer after being or the drug for so long but not knowing your age you could now be into your menopause and this will show with the blood test. hope this helps you. good luck
after being on tamoxifen for 7 yrs and no period for 9 yrs can i still get pregnant?