NED but have concerns about starting tamoxifen

Balentine said:

Thanks for your quick reply
Thank you Sue for replying so quickly....I feel like I am going crazy here. I have already been going through major paranoid feelings about a recurrence and researching diets after chemo to make sure I am eating right. You try to do everything you can to keep from having this beast re-enter your life then I was anticipating see my onc all weekend. Then when I finally get to see him its like I have to pull information out of him and he is the lead oncologist at this cancer center. It is very frustrating but that is also what I was thinking....why didn't he recommend a different therapy?? When the nurse calls me back I plan to ask her to schedule me with a different oncologist to get another opinion. I have the tamoxifen here but I will not start it until I get some questions answered and I feel in my heart that God is leading me to go through with it. My IDC was stage 1, 2cm lump and I have a mastectomy with 3 nodes removed and no cancer in lymph nodes, 4 rounds of taxotere and cytoxan so maybe I am better off stopping here and not taking anything else.
Lorrie

You're welcome Lorrie. And,
You're welcome Lorrie. And, thank you for the scriptures you post. I really like them.

Unfortunately, we all do have the fear of a recurrence, but, the important thing is to do all that you can to improve your chances of it not happening. And, you also have to try, and, I say try, to live a good and happy life. I know it is difficult when you are still in treatment, but, please try. Don't let your fears consume you. If you need an antidepressant, like I said, there are a few that are safe to take that might help you.

That is best to see another oncologist, and, be up front with him. Tell him you need answers and you need everything explained to you. If you can, take someone with you to write down information and just for another pair of listening ears. My hubby even took a tape recorder sometimes. Speak up! You are paying for that oncologist, he works for you, so, make him earn his money.

Everyone has to do what they feel is right for them. Some take tamox and some choose not to. Just get all of the facts and feel comfortable with them.

NED and Lorrie! Great news!!!

Balentine said:

You are right!
Yes....taking certain SSRI's can interfere with tamoxifen's effectiveness and everything else you said also is correct from what I am being told. I think the biggest question for us all if you are taking or will take tamoxifen is....who knows or how do you really know when you actually become post-menopausal? That is the question of the day because once that occurs, taking tamoxifen after menopause becomes a risk factor for getting breast cancer again.
Lorrie

You are dancing with NED! I
You are dancing with NED! I am so happy for you!

I must say that I think you would be better off in seeking a 2nd opinion too.

Good luck Lorrie!


Hugs, Jan

Mariannemm said:

Great Topic
I will be starting Tamoxifen next Monday. I had my last chemo today and they gave me a the percription for Tamoxifen. I too take Prozac and I had no idea about the combination. I am going to call tomorrow and check with my onc! Marianne

Congratulations Lorrie on
Congratulations Lorrie on NED!


And, Congrats Marieanne on being a chemo grad!


Such good news!

mimivac said:

Lorrie,
Congrats on being NED!! That's great. As for your situation, I agree it can be complicated. Being a poor metabolizer of Tamoxifen and taking SSRIs are two different issues. I am not a doctor, but here is my understanding. People who are poor metabolizers of Tamoxifen who are pre-menapausal will often do ovaraian suppression therapy (Lupron or similar) or ovary removal along with an AI. I wasn't aware that pre-menapausal women who are poor metabolizers could still take Tamoxifen. This doesn't make sense to me. Did the doctor exmplain that?

As others have explained, taking SSRIs can further interfere with Tamoxifen effectiveness.

I was also under the impression that being in permanent manpause or not could be tested. Waiting 2 years to see? I'm not so sure about that.

I am going to post some stuff a doctor friend posted on another board about Tamoxifen metbolization. I think you are not being treated very well by this oncologist. Even if Tamoxifen is the best drug for you, he should address each and every one of your concerns and you shouldn't have to be in the dark about what to do. That's wrong.

Ok, let me find that post for you....

Mimi

Post about Tamoxifen
This addresses some of the issues of being pre-menapausal versus post-menapausal:

Tamoxifen Metabolism... DNA testing information

"The issue of genetic variations in drug metabolism are complex. There are not clear indications for how to use the genetic typing of the tamoxifen metabolizing unit cyp2d6 in breast cancer treatment. Your oncologists are confused because it is confusing and we (docs and patients) don't have practice guidelines on this issue. I think YSC should take the leadership on summarizing and distributing information about hormonal management for ER+ breast cancers in premenopausal women. YSC medical advisors should weigh in on this with a position statement. Until then...

Tamoxifen is metabolized to the potent anti-estrogen, endoxifen, by the cytochrome P450 (CYP) 2D6 enzyme. It is endoxifen that is most active against ER+ breast cancer. CYP2D6 genetic variation markedly reduces endoxifen plasma concentrations in tamoxifen-treated patients. Potent inhibitors of the CYP2D6 enzyme can inactivate the gene.

Tamoxifen side effects are NOT clearly linked to the type of metabolizer you are or to whether your enzyme is being inhibited. You can't guess whether it's working by whether you have symptoms.

How to interpret your results if you have been tested (studies were done in post menopausal women with tamoxifen dose 20mg daily but biologically likely to also apply to us)

Ultra rapid metabolizer: You rapidly convert tamoxifen to endoxifen. You get maximal benefit.
Extensive metabolizer: You normally convert tamoxifen to endoxifen. You get usual benefit.
Intermediate metabolizer: You have half the capacity to convert tamoxifen to endoxifen. You may or may not get usual benefit.
Poor metabolizer: You have limited capacity to convert tamoxifen to endoxifen. Your concentration of endoxifen is only 25% of that in tamoxifen treated extensive metabolizers. In some studies in postmenopausal women ER+ on tamoxifen 20 mg/d for 5 yrs after diagnosis, poor metabolizers have 70-80% less disease free survival than non-poor metabolizers.

Based on my opinion as a doctor (specialty: geriatrics), researcher (aging immunology), person with breast cancer, AND after a review of available literature these are my thoughts about cyp2d6 gene typing results and tamoxifen.

1) Not everyone needs to be tested. If knowing whether you are a poor metabolizer, intermediate metabolizer, extensive metabolizer, or ultra fast metabolizer would change your treatment plan than you should consider getting tested for your genotype of cyp2d6.
-Like universal precautions where health care professionals use safe practices for blood collection for everyone not just those at high risk of AIDS, etc; all ER+ breast cancer patients on tamoxifen should avoid cyp2d6 inhibitors in order to get the most benefit out of tamoxifen. If you have to use one of the inhibitors (see list posted in metabolizing tamoxifen link) you may want to know your actual cyp2d6 status in order to determine whether the inhibited level of tamoxifen metabolic endproducts still give you enough benefit.
-If you have a small risk of recurrence and tamoxifen is a back up (for example reduces your risk of recurrence from 4% to 2.5%) then whether you get full benefit or 1/4 benefit may not make much of a difference. However if you are at high risk of recurrence and there are other treatment options open to you if you do turn out to be a poor metabolizer (e.g. higher dose of tamoxifen, ovarian suppression, oopherectomy, oopherectomy and aromatase inhibitor) than you may want to be tested.
-Discuss this with your oncologist. Weighing out potential benefits is complicated stuff and needs to be done with the help of an expert (hopefully your oncologist). Discuss benefit of testing and what would you do differently based on the results before you have your oncologist send the test. Don't ask your oncologist to send the test if they are not comfortable with how to interpret it or if they don't have access to someone who does because then you will be left with another bit of information that causes anxiety without resolution.

2) There are no high quality studies in premenopausal women comparing tamoxifen efficacy in survival controlling for cyp2d6 genotype. This doesn't mean we know nothing. It does mean that we have to be careful and thoughtful about applying the existing data in postmenopausal women to ourselves.

3) It appears in a reasonable number of prospective, randomized controlled trials that in postmenopausal ER+ women on tamoxifen patients with decreased tamoxifen metabolism (due to inhibition or genetic variation) had significantly shorter time to recurrence and worse relapse-free survival (RFS) relative to patients with extensive metabolism.

4) If you are a ultra rapid or extensive metabolizer with no contraindication to using tamoxifen as adjuvant therapy for your ER+ breast cancer than keep using it as it will work for you as expected.

5) if you are a intermediate metabolizer or poor metabolizer you may want to consider additional hormonal therapies either in addition to tamoxifen or in place of tamoxifen for your ER+ breast cancer.

Also don't think aromatase inhibitors are free from these issues...genetic variation in the CYP19 gene might be important in the activity of aromatase inhibitors. I'm sure we will hear more in future.

I hope this helps you figure out your own situation. Consumer directed care can push the envelope for better care but sometimes if our providers are not in partnership with you it can create havoc. Discuss all this with your oncologist PRIOR to getting the test. If you need to make multiple appts just to talk about this issue than do so. You should not accept a out and out agreement or refusal to run the test at your request..... you need an oncologist who will engage you about the test and it's value. You should decide together if it will be of value to you."