Absolutely no side effects from Tamoxifen

Dukip, I've been on tamoxifen since 2012 and only had SE for about 2 months, and even those were limited to just some mild- moderate, short lasting hot flashes and moodiness.

Not having SE or having mild ones doesn't necessary mean that medication is not working. Tamoxifen needs to be metabolized by your liver into its active form called endoxifen, which attaches itself to estrogen receptors on cancer cells, and blocking the real estrogen from feeding them.

There is a small percentage of people that don't have ability to metabolize tamoxifen or have only one active alley in their genetic make up that allows it. That is easy to test with an appropriate blood test, and then checking endoxifen levels in your blood.

Having said that, even people with only one active alley can have a great success with tamoxifen. And sometimes people who are potentially extensive metabolizers (both working alleys), of tamoxifen, can accidentally interfere with absorption of this drug in the gut, so there isn't enough metabolized to protect from the estrogen. Many antidepressants and supplements using enzyme CYP 2D6 to be metabolized, can interfere with the metabolism of tamoxifen; also taking calcium supplements less than 6 hours before tamoxifen can affect proper absorption, (calcium can "coat" other medication in the gut, so it cannot be absorbed, and it needs to be absorbed firstbefore it can be transferred to the liver to be metabolized).

For example I had some adverse effects due to taking turmeric supplement. I'm an extensive metabolizer (I was lucky to be accepted into the research and have periodically checked endoxifen levels in my blood), however after taking turmeric supplement for just over a month, my levels dropped by half. Once stopped - I was retested in 3 months and it went back to even higher level. Apparently turmeric needs the same enzyme as tamoxifen to be metabolized.

On another hand, taking Vit D has very positive impact on tamoxifen efficacy.

The bottom line is that there are many factors impacting tamoxifen efficacy, and having or not having SE doesn't necessarily mean anything.

I hope it helps 😊

Maggs

When I started tamoxifen, I asked my oncologist about the CYP2D6 test. She said that she normally recommends it in cases when people have absolutely no side effects from tamoxifen. There is another SERM that is metabolized differently. I'm sorry that I don't remember the name.

Does anyone know how long it takes, on avrage, for the liver to metabolize the 20mg tamox tablet? I take mine in the morning and 12 hours later take turmeric, thinking that the time gap should help prevent interactions. Would like to know for sure.

Dukip , I have no effects either. My oncologist told me that only 30% of women have noticeable SE's from Tamoxifen: how true that is I have no idea. Of course, we never hear from those that have nothing or very little because they have nothing to complain about - just to clarify I don't mean that in a heartless way, I know many women suffer in a horrible manner with this drug. My oncologist (nor any in my vicinity, I called lots!) doesn't do any testing either - something I found a little disconcerting at first, especially as I had bilateral BC at 41. Thankfully it was stage 1 but none the less it is scary that both 'girls' were behaving badly but there is little follow up. My OB told me that the younger you are the less likely you are to have SE's? She also said that being fit has a large impact on SE's, too.

I found that understanding that Tamoxifen doesn't really block estrogen production helped me feel more comfortable with no SE's. Instead it modulates or 'sits' in the estrogen receptors in the breast so they can not receive estrogen and therefore cannot grow .Tamoxifen can, however, 'stimulate' other estrogen receptors in the body - in the bone, liver and uterine cells. AI's actually block estrogen production by blocking the enzyme aromatase: the two types of treatment work quite differently. You can read about it here:

http://www.breastcancer.org/treatment/hormonal/ser...

http://www.breastcancer.org/treatment/hormonal/aro...

Never hurts to chat with your oncologist but mine told me to enjoy the ride as it can change down the road. The effects can be accumulative and come on at anytime....or not at all. She told me to remember lots of women would LOVE to be in your position.....pretty sound advice: basically be thankful for small mercies. lol

Hi dukip, I'm 1 year in and no SEs for me either.