Are regular periods on Tamoxifen bad?

kika2013

Hi, all--

I wonder if anyone with a more interested oncologist than mine can speak to this issue. I was diagnosed at 42, very pre-menopausal, and have been on Tamoxifen for two years. I got my period pretty regularly for the first 8 months, then irregularly, then not at all for about 6 months. This fall, it has started again on its normal monthly schedule (I was very regular pre-cancer/Tamox). This is great in many ways because I also have a thyroid issue and the insane hormonal shifts were making it impossible to keep that medication dose correct, plus all the hair I lost is finally starting to grow back.

But...I'm concerned that I'm getting a period every month again. Isn't one of the points of Tamoxifen that it stops it so as to prevent the spikes in estrogen, etc? My cancer was highly ER positive so this worries me. I mentioned to my onc at my last visit about a month ago that my cycle seems to have returned and she was very nonchalant, oh it's fine, not worth discussing. But still, I'm nervous, especially after the months of irregular periods and then none at all. It makes me feel like my body is somehow over-riding the Tamoxifen (a feeling I fully realize is based on absolutely no science whatsoever!). And my oncologist, to whom I was sent after doing surgery elsewhere (I was in a different state) has never been very engaged with anything I say to her.

Is anyone in this same boat? I was very lucky with my diagnosis, a small IDC with an extremely low oncotype, but somehow that doesn't make the worry any less real when it happens.

Thanks so much to for any input you can offer on this--google is...well, you know! Google! I can find any answer I want and/or don't want out there!

ShetlandPony

Hi, Kika. I was also diagnosed when premenopausal, and I will try to share some things I learned about tamoxifen. First, it works by fitting in the estrogen receptor on cancer (that may or may not be present) so it can't "feed" on real estrogen. So tamoxifen is not designed to stop your hormone cycle and your periods. One good thing about having periods is that it is thought to negate tamoxifen's very small risk of endometrial cancer because the uterus is getting "cleared out". Second, while tamoxifen can mess with your periods and your hormones, periods are not a reliable indicator of whether tamoxifen is working, or of your hormonal status when you are on tamoxifen. To check your hormonal status you can have a blood test to check your estradiol. That would give the doctors an idea of whether your levels are in normal premenopausal range, or abnormally high, or low enough to suggest you are heading toward menopause. Your gynecologist could order and interpret this test. But what would your doctors do with the information? If your levels are normal or low, that might reassure you. If your levels are abnormally high (as in my case with no periods), would they and you consider ovarian suppression or oophorectomy along with the tamoxifen or an aromatase inhibitor? What would be the risks vs. benefits?

I don't like hearing that your onc is so uninterested and does not answer your questions adequately. I had one of those and I fired him. If your onc is not concerned, she needs to explain why so you can feel reassured. She needs to remember that low risk does not mean no risk, and that you deserve to have your concerns addressed. It is your body and your health, including your mental health. Our mental health does not benefit from worry and stress that a caring doctor could help alleviate.

Jodi040812

Same boat!! I'm 41 now and I have had 3 periods since October. They are like 2 days regular and then spotting for several days. I take tamoxifen. My cancer was 98% ER +, so it freaks me out too! My NP at the ONC office blew it off too. I never see my MO anymore. Annoying!! But, my platelets are low and have been for a year and a half now which is since I started tamoxifen. I have to go back to MDA Monday for bloodwork with an internist. I'll ask about the periods and post back what they say