DCIS and microinvasion & decided against hormone therapy?

I had 6+cm of multi-centric high grade DCIS with comedonecrosis, one 1mm microinvasion of IDC, clear nodes. I had a UMX.  

To my surprise, my oncologist recommended against Tamoxifen for me, although he was willing to prescribe it.  But after doing my own research, I agreed with him.  Here's why.

Hormone therapy provides 3 benefits.  

- The first is a reduction of about 45% in the risk of a local recurrence. For most women, unless they are BRCA positive or have very close surgical margins, after a MX the risk of
a local recurrence is only 1%-2%. For me, this meant that the approx. 45% reduction in risk
from Tamox would give me a risk reduction benefit of less than 1% (and possibly only a 1/2 a percent).

- The second benefit is that it reduces the risk of a distant recurrence, i.e. the possible development of mets.  For those who have pure DCIS, there is no benefit here at all, since there is no risk of mets.  However for those who have invasive cancer, this is often most significant benefit.  With my microinvasion, I fell in-between. I was Stage I, but with just a
small microinvasion, my oncologist assessed my risk of mets to be only about 1%.  So here again the
benefit from Tamoxifen was negligible.

- The third benefit is a 45% reduction in the risk that a new primary cancer might develop in either breast.  For those who've had a BMX, the risk of a new primary is only 1% - 2%, so the benefit is very small.  For those who've had a UMX or a lumpectomy and who therefore still have one or two natural breasts, the risk of a new cancer is obviously higher, and so the benefit will be greater.  My oncologist told me that my risk to be diagnosed again with BC was about double that of the average woman my age. I was 49 when I was diagnosed, and the average 49 year old
has an 11% remaining lifetime risk (to age 90). So that made my risk
22%. If I took Tamoxifen for 5 years (in those days it was only given
for 5 years, not 10), it would reduce my risk by about 45% for those 5
years and would provide a carryover benefit for about another 3 or 4
years. But here's the thing. Of my 22% 'remaining lifetime' risk - which was my total risk spread over 41 years from age 49 to age 90 - only about 4% of that risk would be
over the next 9 years - which meant that my benefit from Tamoxifen
would in fact be a bit less than 2% - not much at all. 

As you noted, Tamoxifen comes with risks of it's own - depending on your health and age, the risk of serious side effects might range from about 1% to as much as 4% (for those who have pre-existing conditions or family history).  When I assessed my breast cancer risk and the relatively small risk reduction benefit I'd get from Tamoxifen, I decided that I could live more comfortably with my BC risk level rather than expose myself to a new set of risks from Tamoxifen, for such a small benefit. 

I made that decision 9 years ago, which means that I'm now beyond the period where I would have had any benefit from taking Tamoxifen for 5 years.  I have not been diagnosed during these 9 years so in hindsight I can say that this turned out to be the right decision.  Additionally, while I still have double the
risk of the average woman my age, because I'm 9 years older and have fewer years left
in my 'remaining lifetime', my risk now is about 17% - 18%.  

The thing to understand, of course, is that everyone's situation is different.  Someone else in my exact situation might be less comfortable than I was living with a 22% risk, and might choose to take Tamoxifen for peace of mind.   Someone who is diagnosed at a younger age will have a higher risk, simply by virtue of being younger and having more years left in her 'remaining lifetime'.  Today Tamoxifen is given for 10 years, and that alone will more than double the benefit for those who choose to stay on Tamox for the full 10 years.  Lastly, in your case, your invasive cancer is ILC, and ILC is thought to confer a higher risk of a contralateral cancer than IDC.  So adding that all together, your risk likely is higher than mine, and your benefit from Tamoxifen might be quite a bit higher.  That doesn't mean that you should take Tamoxifen - it's just changes (i.e. individualizes) the benefit vs. risk ratio on which you base your decision.  

Hope that helps.

I was post-menopausal, but just.  Still; that meant Arimidex and not Tamoxifen.  Because of the "low-aggression" markers of my micro-tumor, my chance of recurrence is small. Say, 6-14% (they can't be sure).  I did not even have a node biopsy, but did see that they looked for lymph or vascular vessel involvement, and there was none.  I was also told that hormone therapy was up to me.  They were not aggressive about it, as the reduction of 45% would, in my case, result in a 3-7% absolute reduction.  It's a very personal thing.  My new MO, whom I love, agreed with my reasoning.  I have a low recurrence chance.  I work in restaurants, and cannot have even a several-months adaption period of bone and joint pain.  I've had protracted hot flashes for 14 years, life-altering, all through peri-menopause and worse in menopause.  He told me that some people want even a 1% reduction, and some people can tolerate not having a 3-7% reduction chance.  I can live with my decision.  I was told by my docs that ongoing, real exercise cuts recurrence by over 30%, so I'm doing that.  Even if I have a recurrence, I would not be able to know if it would have happened anyway, as the hormone therapy helps only half of the time.  Very simply, I could not imagine my body, my joints, the hot flashes, being worse than they are now.  So.  I'm good.  BC brings us face-to-face with life-changing decisions; many of them, and that's a hard road.  At some point, having done your research and having talked to your docs, you just decide, and go on.  I will say that if they had thought I had a 20-30% recurrence chance, I would have taken the drugs and lived with the side efects.  Hope that helps. xx