Tamoxifen

I just started on Tamoxifen this week but I can tell you that my MO wants me on it for 10 years. My ER receptor is 100% (99.8%) positive so I assumed that is why he is saying 10 years. Also, even though I am 53 I am peri-menopausal so that factors into the timeline as well. However, I only had an 8% risk of it coming back based on my Oncotype score and my stats look similar to yours. I do have a genetic mutation as well, which increases my risk for a new primary as well.

I think 10 years is standard of care now. I was told early on I would take it for 10 years. I have a family member who had estrogen positive recurrence 17 years after initial treatment so there's no way I escape the long process of medication.

My understanding is that the tamoxifen, instead of lowering estrogen, blocks the estrogen receptor sites in the tumor cells. So even if you naturally lowered your estrogen, if you aren't blocking those receptors, it's not protecting you as well as the meds would. You probably can't lower your estrogen enough on your own (without drastic measures like ovary removal or suppression) to starve out tumor cells. But I think even when they take out your ovaries, you still need meds.

I am nearly finished 4 years on tamoxifen, fully er pr positive, no node involvement but a high oncotype result. In May this year my Onc agreed that I would be fine to cut my dosage in half so I take 20 g every second day. I was very happy to hear him say I could be done tam after 5 years. I was told I could be advised to take it for 10 when I first started but I think based on my recurrence scores after chemo with and without tam, he is satisfied that I've received probably the max benefit. I see him in December for what is likely to be my second last, or last visit with him. I will be 5 years from diagnosis March 2020.

Lantana70, it's probably because that's the newer way to go based on newer research. Probably not all the docs are doing that yet. Mine is, she said it's what they are moving towards.