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Jan 7, 2009 12:13PM
Generally it's considered that the line in the sand for chemo is an invasive tumor that is 1cm in size. If a tumor has very favorable characteristics, then chemo might still not be recommended even for tumors that are a bit larger. On the other hand, if a tumor has very unfavorable characteristics, then chemo might be considered for a tumor that is smaller than 1cm. Unfavorable characteristics include tumors that are highly HER2+ (in which case Herceptin might also be prescribed) and tumors that are ER-/PR- (in this case particularly because the patient would not benefit from Tamoxifen or AIs as an alternative to chemo). I have never heard of BRCA status coming into play on this decision and I was not aware that BRCA cancers might be different than any other breast cancer - I hadn't heard that.
Since you have a tumor that is considered to have unfavorable characteristics, the question is: For someone who has an invasive tumor that is smaller than 1cm but has unfavorable characteristics, at what size of tumor should chemo be considered? According to the NCCN treatment guidelines (which are used by most doctors in the U.S. and elsewhere), the answer is 0.5cm, if the tumor is ER-, PR-, HER2- and the patient is node negative. You can follow through the treatment guidelines decision-tree in this file, on pages 11, 12 and 16: http://www.nccn.org/professionals/physician_gls/PDF/breast.pdf
Given this, I could see that if you had a 0.3cm or 0.4cm tumor with very unfavorable characteristics, a doctor might be conservative and recommend chemo. But with a 0.5mm microinvasion, you fall well below the chemo line. For anyone who is node negative, the reason for prescribing chemo is the general assumption that the larger the tumor, the greater the number of cancer cells and the greater the chance that one or two of those sneaky cancer cells might have escaped the breast unnoticed. So to put it in perspective, with your type of pathology, the base line for considering chemo is a tumor that is 10 times the size of yours (and therefore contains about 10 times as many invasive cancer cells).
By the way, I notice that you mention that your DCIS is grade 3. With only a 0.5mm invasive tumor, were they able to test it for grade? My microinvasion was 1mm and while my DCIS was grade 3, my microinvasion was grade 1. This was very comforting to me. I'm not saying that it would be the same for you, but if your microinvasion hasn't been tested separately from your DCIS, it could be that your microinvasion is not as aggressive as your DCIS.
Hope that helps! I'll be very interested to hear what the docs at Duke say.
Dx 9/15/05, DCIS-MI, 6cm+ Gr3 DCIS w/IDC microinvasion, Stage IA, 0/3 nodes, ER+/PR- “No power so effectually robs the mind of all its powers of acting and reasoning as fear.” Edmund Burke