How many have doctors who only gave them 5mg of tamoxifen

Faith, I thought the studies on this were for DCIS and LCIS, not invasive cancer

Hi Faith1111, I agree with kec1972. The Italian study doctor said as much that the powers to be would not pursue additional studies because the drug was cheap and had been used for many years. I think I have read most of the articles on the studies for the lower dose and its obvious they need more data for IDC. My doctor ordered the 20mg. I took it every day for 2-weeks then one morning I hurt so much I had trouble getting out of bed. I stopped taking it and my pain resolved. Then I started reading everything on this site and online. On my own I split the tablet and took 10mg. Just about a month ago I requested the 10mg tablet from my doctor and started taking 10mg in the morning and 10mg in the evening. So far this has been working for me. I agree with others it helps to slowly get it in your system. It doesn't come in 5mg so you would have to get a pill splitter to half the 10mg. I guess what I am trying to say is your doctor might not agree, but you have to do what works for you. Some people don't have any side effects or they are minor. Good luck to you!!

Dorothy thanks for posting that study. I find it very encouraging. Makes me feel better about taking a half dose

I just got my Tamoxifen prescription and haven't filled it yet. Very nervous about side effects. I was DX with DCIS but since they also found a very small amount of IDC, my doctor isn't comfortable putting me on the lower dose.

Good luck, Faith! Thanks for sharing your story and your decision.

The low does is for DCIS I have non invasive he put me on 20 mg to start with I told my Dr if the 20 becomes to much I will drop it down to 10 if thats to much 5 he said its better to take something then nothing and agreed with me the one Dr in Italy only id a 3 years research on it not long enough .

Today I found this: https://academic.oup.com/jnci/article/95/11/779/25... which includes "Background: Tamoxifen reduces the risk of breast cancer in women at high risk for the disease but increases the risk for endometrial tumors and venous thromboembolisms, possibly in a dose-dependent fashion. We compared the effects of tamoxifen at 1 mg/day and 5 mg/day with those of the standard dose of 20 mg/day on breast cancer proliferation using a surrogate endpoint marker (Ki-67 expression) and blood biomarkers associated with breast cancer . . . . Methods: We randomly assigned 120 women with estrogen receptor (ER)-positive breast cancer to tamoxifen at 1, 5, or 20 mg/day for 4 weeks. Expression of the tumor proliferation marker Ki-67 and of biomarkers of breast cancer (insulin-like growth factor-I, sex hormone-binding globulin) . . . risk were determined before (baseline) and after treatment. All levels were compared with those in two nonrandomized control groups (34 women with ER-negative breast cancer and 29 additional women with ER-positive breast cancer). . . . Results: Expression of Ki-67 decreased in all three tamoxifen groups, with no difference in the magnitude of reduction among groups . . . Relative to baseline, Ki-67 expression decreased by a median of 15.0% . . . among the tamoxifen groups but increased by 12.8% . . . among the nonrandomized control groups. Several blood biomarkers showed dose–response relationships with tamoxifen, including decreased insulin-like growth factor-I, increased sex hormone-binding globulin . . . levels. Conclusions: The effects on Ki-67 expression of lower doses of tamoxifen were comparable to those achieved with the standard dose, although the effects on blood biomarkers were variable. The effects of lower doses of tamoxifen should be assessed further in randomized trials."

I'm happy to see another study that says that less than 20 mg / day might be effective for those of us with stage 1 cancer.

However, the previous study that I've linked before https://www.researchgate.net/publication/12740517_... had slightly different results. This link includes "Tamoxifen administered at 20 mg/d has been shown to decrease breast cancer incidence in at-risk women by 50%, but toxicity may limit its broad use, particularly in postmenopausal women. Because toxicity may be dose-dependent, we studied the biologic activity of low concentrations of tamoxifen to determine the plausibility of a dose reduction. We measured the blood concentrations of tamoxifen and its main metabolites in a dose titration study in 105 healthy women (placebo, tamoxifen 10 mg on alternate days, tamoxifen 10 mg/d, and tamoxifen 20 mg/d). Drug levels measured after 2 months of treatment were correlated with the changes in surrogate biomarkers of different diseases, including . . . insulin-like growth factor I, a promising surrogate biomarker of breast cancer. The means . . for tamoxifen and N-desmethyltamoxifen (metabolite X) concentrations (ng/mL) were dose-related, being, respectively, 0 and 0 with placebo, 26.8 +/- 15.1 and 43.7 +/- 22.5 with 10 mg every other day, 51.2 +/- 24.1 and 90.7 +/- 48.0 with 10 mg/d, and 136.0 +/- 52.7 and 230.6 +/- 75.0 with 20 mg/d of tamoxifen. At variance, the biomarker changes were of comparable magnitude at any drug concentration . . . . An 80% reduction in blood concentrations does not seem to affect the activity of tamoxifen on biomarkers of . . . breast cancer risk and may in fact have a more favorable safety profile. Additional studies are warranted to determine the most appropriate dose of this agent.

My reading of the second study seems to indicate that decreasing the dose of tamoxifen does not decrease the change in the breast cancer biomarker "insulin-like growth factor I" but the first study said "Several blood biomarkers showed dose–response relationships with tamoxifen, including decreased insulin-like growth factor-I . . . levels."

Curious if Beesie or anyone else has anything to add to my understanding of these two studies?

Thanks!

CareBearKid4Life - I never made it up to the 20 mg. After several weeks on 12.5 mg, my side effects were bad enough that I went back down to 10 mg. My med onc is totally against me taking anything less than 20 mg. However, I am choosing to stay at 10 mg against medical advice. To me having reasonable quality of life is important. At 10 mg, my side effects are manageable with the worst being leg cramps most nights.

Hi all!

I’m in a similar position. I started Tamoxifen in February 2016. After almost 3 years at 20mg (and stopping and starting weeks at a time), I starting have horrible side effects. Every joint hurt and I felt like I was 90 years old. I was miserable! I tried to take myself off it completely but my estrogen came roaring back and I had acne and V. Painful breasts. It scared me but I read the study suggesting 10mg was possibly as effective as 20mg. I decided (on my own) to lower my dose to 10mg a day and have had zero (or close to it) side effects. I’m now on my last few months of my Tamoxifen journey (pending clear scans in Jan). I have no regrets and although I never told my MO, I feel for me it’s better than nothing. I also do alternative medicines’ along side with tamoxifen so hoping both can help keep me clear.