What is this "microinvasion" all about?

Nursepatient35

Wondering what this microinvasion talk is all about? I was diagnosed with a small DCIS and will be having a double mx with TE's placed next week. I thought DCIS is all contained but then I see people posting about having a microinvasion. Now I'm worried. Would a bmx take care of this if I did end up having a microinvasion? Or would a person need chemo afterwards? My mind is starting to go all over the place now that surgery is near.

Annette47

A micro-invasion means a very small area (<1mm) of invasive cancer was found with the DCIS. In the vast majority of cases, with a true micro invasion (as opposed to a still small but slightly larger area) it doesn’t change the treatment plan in the least. A BMX would usually be enough to take care of it.

I had one and the only change it made to my treatment plan was that they decided to do a sentinel node biopsy along with my lumpectomy, which is usually done with a bmx anyway.

Beesie

DCIS is all contained.

However, most IDC (invasive ductal carcinoma) develops from DCIS. So what starts out as DCIS can progress to become invasive cancer, if it is not found and removed/killed off (with surgery and/or radiation and/or hormone therapy) before that happens.

Women who have DCIS-Mi often think of themselves as being "DCIS patients" and tend to post in the DCIS forum, however DCIS with a microinvasion (DCIS-Mi) is in fact Stage I Invasive Cancer, whereas pure DCIS is Stage 0. A microinvasion is simply a very tiny invasive cancer, defined as being no larger than 1mm in size. From a staging perspective, it is classified as a 't1mi' tumor. DCIS is classified as a 't0' tumor.

After an initial needle biopsy finds DCIS, there is about a 20% risk that some invasive cancer (ranging from a single microinvasion to anything more) will be found when the surgery is done. For those who have large amounts of DCIS, and particularly aggressive DCIS (high grade, presence of comedonecrosis), the risk is higher.

Part of the confusion on this site comes from the fact that within the Profile settings, there is no place to enter "DCIS-Mi" as a diagnosis. Since many of us who have DCIS-Mi have a large amount of DCIS (I had over 7cm) with just a tiny amount of invasive cancer (I had just one 1mm microinvasion), the tendency therefore is to identify the diagnosis as being DCIS rather than IDC. This in turns leads to an incorrect stage designation, since the profile settings default DCIS (correctly, when the diagnosis really is DCIS) to Stage 0, whereas DCIS-Mi should be identified as being Stage I.

This graphic helps explain DCIS-Mi. You can see that with DCIS, the abnormal cells are fully contained in the duct. With DCIS-Mi (2nd from bottom), the duct looks just like it does with DCIS but in addition, a few of the abnormal cells have broken through the duct wall to become invasive cancer within the open breast tissue.

The source of this graphic is BCO (http://www.breastcancer.org/pictures/types/dcis/dcis_range) but note that on the page linked, the graphic is mislabeled. This does not show the "Range of Ductal Carcinoma in situ (DCIS)" but shows the 'progression from normal breast cells to invasive breast cancer'.

As Annette mentioned, the presence of a microinvasion usually does not change the treatment plan, except for the need to check the nodes with an SNB (which is not necessary for those who have pure DCIS, although an SNB may be done for those having a MX). However, there are exceptions to the rule. Should someone be found to have several microinvasions and should the microinvasions be HER2+, this could significantly change the treatment plan. Any one with this diagnosis would probably move away from the DCIS forum and move over to the invasive cancer forums.

Nursepatient35

Beesie, thank you for the info. It is confusing but I think I get it. The doctors have always said it's DCIS but then my path report said it would be sent off for further horomone receptor testing which still hasn't been resulted. I guess I'm just assuming no one is too worried about this since I decided on a bmx and it will all be gone anyways. I just don't want to wake up from surgery with any surprises that something spread and I'll now need more treatment. I also was told they probably won't do a sentinel node bx unless she suspects maybe it spread when she gets in there.