Uterine Lining thickening on Tamoxifen

Hello Marycal, I only recently started on Tamoxifen but went for baseline measures and was told that the lining should not exceed 5mm. Anything greater we would need to do additional tests. I have not sought to check this with anyone else. My MO and gyn advised as such. My lining was 2mm. This is pre tamoxifen so will see in the next 6 months.

The information about glands is interesting, I will also ask more about that.

All the best, Please share any updates.

Coraleliz, re: polyps. I too had thickening of up to 16mm which I only knew because I had a huge period 16 years after menopause and after 4 years of Tamoxifen. My doctor said 4mm was normal.

I had a D & C after 6 months of procrastinating and doing a "wait and see" with many US in between. A polyp was found and the doctor said that these do not become malignant ever which is contrary to what you were told. Who knows what to believe? Three uterine biopsies were negative. Six months after the D & C, I had another period although I had stopped the Tamoxifen a year prior to this point. The lining was 12 after being off T that long. I declined another D & C and she offered a saline sonogram three months later which said my lining was "normal". I wait; don't know if this is over.

Good luck with your situation. I'm sorry you have had to have repeated polyps removed. My advice is not to do anything radical especially if there's a negative biopsy.

The thicker the lining and the longer it continues without a period, the more concern there may be in the future. I read 11mm should be the cut off, but there's always updated information and it has been over 8 years since I've been on it. I did end up with 3 polyps (I was on tamox for 3 years and arimidex for 2) a few years after I stopped all antihormonals. Thankfully, mine was b-9. My gyn in WI told me it would be 3% risk of the polyps being cancerous.

Here is the article: https://www.ncbi.nlm.nih.gov/pubmed/15386607

As an aside, tamoxifen naturally thickens the lining which is why women are told to get screenings when on it---it acts as estrogen in the uterus.

Chemo stopped my very regular periods at age 50. About eight months later, I started Tamoxifen. Both my MO and my GYN declined to do any baseline US - stating that there is no guidance for how often they should be done or what cut offs should be used. They only advised me to follow up on any bleeding as that could be concerning.

I quit taking the Tamoxifen after three months due to too many problems with SE's. A few months later I had an episode of fairly severe abdominal and groin pain. My PCP sent me for an US - thickened lining (1.2 cm) and ovarian cyst. My GYN recommended to repeat US in three months. That one showed lining of 1.6 cm and cyst had become septated! GYN's advice was for D&C with possible ovary removal.

And then I had a period - 18 months after my last one! Another US done a couple of months later showed a lining of 0.3 cm and no ovarian cysts.

I have a new GYN. She would like me to be on Tamoxifen - as would my MO. I know that the risk of uterine cancer is very low. And my risk for recurrence is much more concerning. I just really don't feel like dealing with any more problems. I wish there was better guidance on these things.

Yes - would like to just be done and move on! Conflicting opinions and practices of various physicians make things extra hard. It's like a full time job to figure out what's best.

Hormone levels fluctuate so it's difficult to rely on them. Premenopausal endometrial thickness varies quite a bit due to hormone influence. Postmenopausal thickness should remain thin. Tamoxifen causes changes that I guess are just not that consistent from woman to woman.

Personally - I worry less about possible uterine cancer than I do about the effects of a thickened lining, polyps, cysts, etc