I took letrozole for over 15 years, was in recovery from breast cancer (lumpectomy) in 2005 ....had a great run until 2024, when I was diagnosed again with breast cancer, same breast. I had a double masectomy at that point. no chemo, no radiation - and I'm taking letrozole again. Ask your doctor about adding some vitamins, especially B6 and B12 (also D3) It really helps with fatigue. Don't overtake either one, look up your age and take that amount, unless your doctor says differently. I really believe letrozole staved off getting cancer again, and that I should have never stopped taking it. The side affects definitely outweigh getting breast cancer again. Non-caffeine herbal teas also are helpful, especially in the mid-afternoon. Good luck and hang in there....