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Oct 24, 2020 12:23PM
Microinvasions are more commonly found with grade 3 DCIS (as I had) but yes, I've seen other people come through here who've had a microinvasion with grade 1 DCIS.
As for the AI, there are three risk reduction benefits you will get:
First is an approx. 50% reduction in the risk of local recurrence. After a MX, your risk of local (in the breast area) recurrence is 1%-2%, so at most, taking an AI provides a 1% benefit.
Second is an approx. 35% reduction in the risk of a metastatic recurrence. With only a microinvasion, your risk of mets is about 1% - at least that's what my oncologist told me when I had a microinvasion. So that's less than a 0.5% benefit (basically what PREDICT told you).
Third is an approx. 50% reduction in the risk of developing a new primary breast cancer in your remaining natural breast. Having had breast cancer once, your risk to be diagnosed again is higher than the average woman. And you are soon to be entering the highest breast cancer risk years for all women - we are all highest risk to develop breast cancer between the ages of 60 to about 75. So the risk reduction benefit here, if you take an AI for 5 years (the benefit will extend for a number of years beyond that) is probably in the range of 3%-4%, or possibly higher, if your risk is higher based on personal risk factors.
What my MO explained to me is that for the DCIS-Mi itself, the benefit vs. risk equation for endocrine therapy (either Tamoxifen or an AI) doesn't work out in favor of endocrine therapy, simply because the risk after a MX and with only a microinvasion is already so low. But there can be significant benefit to endocrine therapy as protection of the remaining breast. But if you go ahead and have the other breast removed prophylactically, then you face a situation where the serious and qualiy-of-life risks from the AI may actually outweigh the small risk reduction benefit you would get from the AI. Now of course all this is based on my personal experiences and discussions with my MO, as well as what I've seen in posts from others here who've had a DCIS-Mi diagnosis. If you have not done so, you should have this benefit vs. risk discussion with your doctor.
And I agree with MinusTwo, with the microinvasion, and for a discussion about endocrine therapy, you should be seeing an MO.
“No power so effectually robs the mind of all its powers of acting and reasoning as fear.” Edmund Burke