Does Tamoxifen Cause Uterine Cancer: I Can’t Believe It

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Does Tamoxifen cause uterine cancer? It can be in women who are menopausal and have taken the drug for greater than 2 years.

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Does Tamoxifen cause uterine cancer?  It can be in women who are menopausal and have taken the drug for greater than 2 years.

Another step in my breast cancer journey. It has been quite a journey that’s for sure. I know that many people think that once you’re done with the “hardcore treatment” like chemotherapy, radiation, etc that it’s all over with and life goes back to normal. It doesn’t.

This is how I explain life with cancer. It’s like a tornado. First, you’re just trying to survive the tornado things are flying everywhere (you’re going through tests, waiting, surgery, treatments, etc). Then when you finish the big treatment comes the aftermath of the tornado, destruction is everywhere. You go through all of the rubble (what just happened to me, and the emotions hit you like a ton of bricks). Now you have to rebuild your house, but it cannot be the same house. You have major changes that need to happen. You have to eat differently, eliminate things from your life, exercise even more, etc. Plus your perspective of the world around you and of yourself has changed.

Does Tamoxifen Cause Uterine Cancer

I have been in the aftermath stage and still on my endocrine hormone-blocking therapy for 3 years now. The drug’s name is Tamoxifen and it puts you in chemical menopause to give your healthy cells time to kill any cancer cells that remain after treatment.

After radiation, I ironically went naturally into menopause. My doctors said it is unrelated to my cancer treatment. When you are in menopause, you are supposed to change to a different medication called Anastrozole. Unfortunately, I wasn’t a good candidate for this new medication as it degenerates bones, and my bone DEXA scan is showing that I’m osteopenia. Therefore I needed to stay on Tamoxifen. When you’re in menopause there is an increased risk that it could cause uterine cancer. I was told to watch for spotting as a major sign that there is a problem.

About a week ago, I started spotting so I immediately called the doctor. They told me to stop taking the medication temporarily, and get bloodwork done a transvaginal ultrasound, and a pelvic exam. The bloodwork came back confirming I was still in menopause. The ultrasound came back that my uterine lining was much thicker than it should be (5mm is normal and mine was 23 mm). I went in for my pelvic exam which came back clear and they immediately did a biopsy as recommended by the ultrasound results. Luckily the biopsy came back clear.

Did all of the emotions come back – absolutely! It was very triggering to go through all of that.

What’s next? I meet with a doctor to go over my next steps. I will need surgery regardless. If I do nothing the uterine lining will release on its own at some point causing mass bleeding and making me anemic. I will end up in the ER. So right now they have said my options will be a DNC surgery where they scrape out the uterine lining or a hysterectomy.

The fact that the uterine lining has gotten thick also shows that the cells are acting abnormally. This can result in precancerous and then cancerous cells forming down the road.

My oncologist wants to meet after my next appointment with the gynecologist, she wants to meet and go over everything. As of right now, my options are looking like this:

  1. Resume tamoxifen, with close follow-up through your gynecologist.
  2. Switch to anastrozole to complete 5 years of endocrine therapy (the downside is bone health).
  3. Stop endocrine therapy a couple of years early (means accepting a higher risk of cancer recurrence or new breast cancer than if you had completed 5 years, but recurrences are almost always curable since we are watching you carefully).

My thoughts, I’m honestly leaning toward a hysterectomy and oophorectomy. My sister and mom both have had breast cancer yet, we show no genes linked to it. My mom has also had another cancer of unknown source that has the same genetic disposition of uterine, ovarian, lung, and colon cancers and more. I am already in menopause, so removing them won’t affect that at all. I am not planning on having any children, and it would decrease my risks of ovarian and uterine cancer down the road.

Is there a link between breast cancer and uterine cancer?

People who have had breast cancer, ovarian cancer, and colon cancer are at a higher risk for uterine cancer.

How common is uterine cancer from tamoxifen?

There is no known risk for premenopausal women. The risk is low, less than 1% a year.

How does tamoxifen affect uterus?

Tamoxifen is associated with an increased risk of developing endometrial polyps, endometrial hyperplasia, and cancer, uterine sarcoma.


After discussing all of the options with both the OB/GYN surgeon and my oncologist, we decided to do an ablation and stop taking Tamoxifen. This would be the least invasive approach. The ablation when well, and the uterine tissue came back normal, however, there was a polyp the size of my uterus. Interesting that that wasn’t found in the ultrasound. The polyp had some abnormalities to it. It was on its way to becoming pre-cancerous. The next step for me will be to have an ultrasound to see if any of the tissue is growing back in 3 months. If it does start to thicken, then we’ll discuss the next steps. If nothing is showing, they said I will just need to watch for abnormal bleeding again.

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Does Tamoxifen cause uterine cancer?  It can be in women who are menopausal and have taken the drug for greater than 2 years.

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  1. Given your history with CA and the time you already been on Tamoxifen, I would support you. In your decision for a total hysterectomy ( Ovaries, tubes, uterus, etc.) It would mean so much less to worry about. It seems your family has a tendency to have CA. If you don’t tolerate the drug substitution for Tamoxifen, or your bones are abnormally sensitive to the new drug and you must come off it to go back on to Tamoxifen, it makes very rational sense, to go ahead.. With the thickening of your uterine walls possibly developing more major problems down the road. Is just proof that a Total hysterectomy is your ultimate solution. It’s possible they might consider a D&C first to prevent a uterine hemorrhage as they plan for the hysterectomy.. it might be the wisest course to prevent an intra procedural hemorrhage when they do the hysterectomy. I’ve had 2 D&C’s, 1 for a possible miscarriage, when I was in my 20’s and a 2nd in my 40’s when my lining got unusually thick, and I developed uterine fibroids, that resulted in a major uterine hemorrhage. Both times I was working. The second happened when I was perimenopausal. They wouldn’t do a hysterectomy as I had hoped but started me on monthly shots of liquid fire, in my butt. Plus a special birth control med that made me stop having periods until full menopause kicked in.. It also rid me of constant battles with implanted uterine masses outside the uterus, can’t remember that diagnosis, but it started when , I was 9yo, and I was 23yo it was finally diagnosed. You said you will meet with your GYN and your oncologist so the will discuss everything that can be done. That way you can make a fully informed decision what to do. Whatever you decide, hope it works for you, for the best outcome. Good luck and practice lots of self care. When I’ve had big issues on my mind I’ve dived into big projects, that take my full attention, also have you tried meditation, guided imagery, progressive relaxation exercises, yoga, total body stretching routines, getting into books that command you full attention, or adult coloring books.Anything that will keep your mind and soul, totally in thrall. I’ve used There is also pastoral or psychological counseling and therapy. You have been going through so much since I signed up for your blog. Take care, and hang in there.

    1. Thank you so much for sharing, I appreciate all of the information and it’s very helpful. I’m so sorry to hear you went through all of that. Thank you for sharing all of your coping ideas too, I really appreciate it.

  2. I’m so sorry you are going through this Chas, my thoughts and prayers are with you. Thank you for sharing; it is such valuable information to know because I really had no idea that Tomixifen could cause issues down the road.

  3. Nancy Nicholas says:

    I’m so excited that you are feeling better and more positive now!!! He never let’s us down!!! Prayers are being answered!!! Continue doing what you’re doing and let Him know how much you you love Him!!! We’re going to keep you lifted and know that you will be fine!!

    Love and Prayers,


    Hi Chaz,

    I admire your courageous approach in this time of difficulty/storms in your life. I know these
    storms will come to pass and you can overcome them with a positive attitude that you have.
    Just believe, trust and surrender everything to God that knows what really is/will be best for
    you. You and your family ( Mom and your Sister) will be in my prayers. Don’t forget that we
    are all precious children of God and He loves US very much!

    Cheers and regards,

    Betty (Beth)

    1. Thank you so much, I truly appreciate it. Hugs to you!

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