Is tamoxifen needed for dcis that was treated with lumpectomy&radiation? been on it for 2yrs&have bad side effects. sonogram showed endometr thickenin

It's risk vs benefit: Tamoxifen drops your risk of developing a new breast cancer in either breast by 1/2. But the absolute benefit is small. You are only 22, so your lifetime risk of having a new breast cancer is higher than if you were 50. Ask your doctor for the numbers (your risk of developing a new breast cancer with or without tamoxifen), and ask about raloxifene, a similar drug. Then make your decision.