More Aggressive 2nd BC as a Result of Tamoxifen Use for DCIS

I opted out because I didn't want the other side effects....  My MO approved my decision and said the risks out weighed the benefits for me.  I've not heard about this issue in the article.

I didn't get offered it as they don't test for er/pr in the UK for pure DCIS.

Rads made me tired, but the Tamox is fine. I guess everyone has different side effects but the main one I get is night sweats and an unpredictable period. I'm only 43, too. All my doctors seem to think that is fairly young & that it means that we still have a lot of time in which to develop a recurrence or new cancer in the other breast. So they are telling me that even though it was just DCIS,it was a red flag, and I should be aggressive and hit it with everything. Tamox is nothing compared to MX and chemo, right? But if your MO isn't pushing it, then maybe she has her reasons...

Something else to keep in mind about Tamoxifen.  If you are 43 now, your breast cancer risk spans the rest of our life, which hopefully goes on for another 40 to 50 years.  For most women, their highest risk years for BC are when they are in their late 50s, 60s and 70s.  5 years of Tamoxifen reduces BC risk by about 45% but it doesn't keep working for 40 years.... the studies I've seen suggest that you get the full benefit for about 10 years and a declining benefit for another 5 years or so.  That's not a reason to not take Tamoxifen, but it means that if you want to continue to reduce your BC risk after the benefits from Tamoxifen start to decline, you need to move on to another drug, likely an AI.  It also means that if your 'lifetime' risk of breast cancer is 20%, Tamoxifen will not reduce your risk to 11%.  Your lifetime risk is spread over the rest of your life; Tamoxifen will only provide a benefit against the portion of that risk that occurs over the next 10 - 15 years. 

I was diagnosed at 49 and had a single MX.  My oncologist actually recommended against Tamoxifen for me at that time, saying that if I were to take it, it might make sense to wait until I was in my higher risk years.  At the time, he estimated my remaining lifetime risk to be about 22% (about double that of the average 49 year old).  My risk over the next 15 years, however, was less than 8%.  So Tamoxifen's benefit for me, assuming a full 45% reduction in my risk for 15 years, would have been about 3.5%. It would have taken my lifetime risk from 22% down to 18.5%.  I'm now 56 and my lifetime risk is down to about 18% (lifetime risk goes down every year simply because there are fewer years left in our lifetimes). I realize that I'm now getting to the years where I would get the greatest benefit from Tamoxifen but after not taking it for all these years, I'm hesitant to start. But I have to admit that I do mull the idea around in my head. 

Hi Aster

Thanks for the article, but I also don't see anywhere that they mention DCIS in it? Do we know if this applies to Invasive as well as non-invasive (DCIS) BC?

Here's what it reads which to me implies it's related to "invasive" BC:

"We conducted a population-based nested case-control study including 367 women diagnosed with both first primary estrogen receptor (ER)–positive invasive breast cancer and second primary contralateral breast cancer and 728 matched control women diagnosed only with a first breast cancer."

http://cancerres.aacrjournals.org/content/69/17/6865.short

NSJ2

Thanks Beesie.

Well that kinda blows. One of the things Tamox is supposed to help prevent is a new primary in the contralateral breast. But if it does occur, this study implies it may be ER neg.

Yes, Tamox does significantly reduce the risk of a new primary.  And the majority of new primaries that develop are still ER+, but compared to women who didn't take Tamoxifen, a higher percentage are ER-. 

I recall seeing the actual %s that are ER+ versus ER- in some report on this study.  I'll see if I can dig it up. 

I recently post a thread called "Tamoxifen & Breast Cancer, an informative, must read book" I don't know how to link the post so you can search. If you want to understand Tamoxifen and how it works/interact/interfere with breast cancer, you may want to check out the book, Tamoxifen & Breast Cancer, by Michael W. DeGregorio and Valerie J. Wiebe. The book was written by a Researcher in CA. The book was given to me, and helped guide my decision. It is NOT an anti-Tamoxifen book, it describes the drug, it short/long terms SE, in language that lay person can understand.  

I just had right breast mx for dcis. Since my tissues we free from any invasive cancer and my sentinel nodes were also clear, surgeon said ' see you in a year' but suggested even though its not necessary that I meet with the (cant remember his official doctor type) oncology doc to establish a relationship???

As a result of a head injury from an auto accident in my mid/late 20s, I had a massive stroke which has left me with a deficit on my left side. I don't want to imagine EVER deliberately taking something that wasn't 200% necessary, that could cause a stroke....been there done that..nfw

As a side note, I turned 47 exactly 1 week after my mx ....