Should I be taking tamoxifen?

thanks Beesie for everything you have written. I'm seeing onc in 2 weeks and I will be better informed because of you.

I went through something similar after my BMX for DCIS. The breast surgeon wanted me on Tamoxifen but the head of the oncology dept. said no. Since DCIS is contained only within the milk ducts, in theory, with the mastectomy, all the cancer is gone so no need for Tamoxifen. I came here looking for advice as well. Beesie helped to realize it was not necessary. In fact, the oncologist told me that the possible side effects could only worsen some health problems I already had. The negatives outweighed what little benefit it would provide.

I am very much of the mind set that I would do all that I can to fight breast cancer. But I decided no to the Tamoxifen after a bmx with DCIS. 

Hi,

   I am new for this discussion board. I am newly diagnosised with DCIS and just finished left-mastectomy on Oct 10. My pathology report came back for no malignacy tissue found.( ER, PR has not tested) Pathologist thought stereocore biopsy have taken all bad tissue. My DCIS ( grade 3 5mm). I have an appointment on Nov 20 with Oncologist. I know I may need to take tamoxifen. I am so scared to take it because of side-effects of it. Does anybody can give me some advice?How this side-effects affect you life?

Many thanks

Hi Jenny, i did both. She didnt recommend tamox because my invasive was small and was removed during my biopsy. And i was left with very little dcis, i think .5mm. She said if i only removed 1 breast i would definetly need tamox. Or if i had a lumpectomy i would need to take it. Both my MO said i would benefit very little from tamox. But im sure if i wanted to take it, she would of prescribed it.

Jennychen, I had a single mastectomy too.  I opted out of Tamoxifen... and that was actually my oncologist's recommendation, much to my surprise.  A lot of women who have single MXs do take Tamoxifen, not so much to reduce recurrence risk but as a way to protect the remaining breast.  It's a question of how much benefit you will get from Tamoxifen, and how much benefit is enough to make it worthwhile for you to try Tamoxifen. The following might help you prepare some questions for your oncologist:

Tamoxifen provides 3 benefits:

1) Approx. a 45% reduction in the risk of a local (in the breast) recurrence.  For someone who had a MX for DCIS, unless you had particularly close margins, your local recurrence risk is likely only 1% - 2%.  So even if it's 2%, at most the benefit from Tamoxifen will be less than 1% (a 45% reduction of a 2% risk).  

2) A reduction in the risk of distant recurrence, i.e. mets. This is the most important benefit for those who have invasive cancer.  For someone who had a diagnosis of pure DCIS, there is no risk of mets so there is no benefit here from Tamoxifen. 

3) A reduction in the risk of developing a new primary BC, in either breast. Tamox. reduces BC risk by approx. 45%; if you take Tamox for the full 5 years, you will get this 45% risk reduction for about 10+ years. You might actually get some benefit for as long as 15 years, although likely at a declining rate of risk reduction in the later years. This is important to understand because often women believe that if they have a 20% chance of developing BC again during their lifetime, Tamox can reduce this risk to 11% (45% reduction of a 20% risk). Not so. How much Tamox actually reduces your risk depends on your risk and on your age. If you are 50 now, you risk developing breast cancer for about the next 40 years. Tamoxifen obviously won't provide a benefit for all that time. The rule of thumb that I've seen is that most women who've had BC have an annual risk to develop a new BC of about 0.5% per year. If your risk is 0.5% per year and you are 50 years old, this means that your remaining lifetime risk, till you are 90, is 20%. Taking Tamox. for 5 years will, in the best case, give you 15 years of risk reduction. Over the next 15 years, your risk is only 7.5% (0.5% per year X 15 years). A 45% risk reduction for the next 15 years would therefore reduce your risk from 7.5% to 4.1% (a 3.4% benefit). This will take your 20% lifetime risk down to 16.6%. That's a rough calculation - what you need to do is ask your oncologist what your annual risk is, based on your health and family health background. Then you can do your own calculation of your benefit from Tamoxifen, using your risk level and your age. 

That's the way that my MO explained Tamoxifen to me. I had a single MX, so my local recurrence benefit was at most 1%. I had a microinvasion of IDC along with my DCIS, so I do have a very small chance of mets, at most about 1%. This means that I'd get a small reduction in my risk of distant recurrence, at most 0.5%. As for protection of  my remaining breast, I was 49 when I was diagnosed so the calculation I did above for a 50 year-old would be about right for me. This means I'd get about a 3.4% reduction in my risk of a new primary BC from Tamoxifen. Looking at that amount of risk reduction, and considering the small risk of serious side effects (1% - 3%, depending on what other health problems you may already have) and the risk of quality of life side effects, I decided that taking Tamoxifen wasn't worth it to me.

All of that isn't to suggest that you might not want to take - or at least try - Tamoxifen. Your benefit might be greater, if you are higher risk, and you may be more willing than I to try Tamoxifen even if the benefit is lower.  But hopefully this explains why the benefits from Tamoxifen are not as significant for someone with DCIS as they are for someone with invasive cancer (who benefits from the reduction in the risk of mets), and the benefits are not as straightforward as you might think.  It's certainly worth a discussion with your oncologist.