New and confused about how DCIS could become stage 1, invasive?

As others have said, that is the million dollar question.  My understanding is that while lifestyle factors may contribute to the overall risk of developing breast cancer (though your biggest risk factors are being female and getting older), there isn't necessarily any research showing they affect when/if DCIS changes to IDC.   One thing that is important to understand that the change happens on a cellular level, one cell at a time, so it's not like the entire area all of a sudden morphs into the same size area of IDC.   What happens is for some unknown reason, one of the DCIS cells mutates into an IDC cell which is capable of breaking through and thriving outside of the ducts.  Then that cell divides over and over growing the IDC portion of the tumor.  Sometimes, that happens very early in the process while the DCIS is still very small (which is what happened in my case) and if not detected early, eventually proportionately there is so much IDC that the tiny bit of DCIS isn't even visible anymore; other times, it doesn't happen until the DCIS has grown very large; sometimes it never happens at all.    Even when IDC develops, the DCIS remains DCIS, but there is now (when that happens) an additional area of IDC.    So even if that were to happen in your case, between now and your surgery, the odds are that it wouldn't get very far or big between now and then - in most cases breast cancer grows very slowly.   I've read several places that it takes on average 3 years for it to get to be big enough to show on imaging, so even if yours were to mutate to IDC tomorrow, in 3 months it would most likely be no more than a micro-invasion, which really wouldn't change your prognosis much.     This is why the surgeons are not usually in such a hurry when someone has been diagnosed with DCIS.     Of course, there is always the possibility that some of your DCIS which might remain in the breast (since the reduction wasn't done specifically to remove the section of DCIS, unless it happened to overlap the area perfectly there is likely some DCIS left) has already begun that process, potentially leaving you with already existing areas of IDC, but that is unlikely, and in any case should be detected by your upcoming MRI.     I would think that your reduction counts as a biopsy, so you shouldn't need an additional one - they know you have cancer (DCIS), the MRI is to see how much you have.   A biopsy wouldn't really add to that information.

Hope that helped a bit.

Here
are some additional thoughts:  On your question about what causes DCIS to
develop an invasive component - nobody knows what triggers that change, or how
to prevent it, short of surgical removal.  There are factors in DCIS
pathology that indicate the level of aggressiveness, and greater likelihood of
development of an invasive component, and that is grade (from 1-3
Bloom-Richardson), size of the area of DCIS, presence of comedo
necrosis, and possibly hormonal markers.  And yes, you are
correct, there is no such thing as invasive DCIS - it is confined to the duct,
and is always stage 0.  On the question of whether there is DCIS remaining in
your breast tissue after reduction - did you have breast imaging done prior to
your reduction?  If so, what type? If you did, it apparently
did not see your known DCIS. Your DCIS is unlikely to change much in the short time prior to your surgery - I had a 2cm IDC, with some DCIS, and had almost a 2 month wait for surgery.  The size of my IDC did not change from what the measurement was initially.  The reason your doctor is interested in testing your lymph nodes is because it is unknown whether or not you have any invasive component, and once the breast tissue is removed they can no longer identify which lymph nodes are your sentinel nodes, the ones most likely to show any cancer spread.  If you remain pure DCIS, with no invasive component, then there is no possible spread to the nodes, but during this surgery is the only time they can determine your sentinel.  They do look at the sentinel nodes pathologically in the OR, but this is a cursory exam.  A more thorough exam in the lab is done after surgery, and sometimes nodes thought to be negative at the time of surgery are found to have cancer.  Whether or not your nodes are positive does not mean that you can't have expanders or implants placed at the time of surgery.  Being unable to do immediate reconstruction, or starting it, is predicated more on chest wall involvement that may require radiation.  Your MRI should help delineate location.  A mastectomy that removes muscle was routinely done years ago, and is called a radical mastectomy.  It is still done if you have known cancer in that location.  The vast majority of mastectomies done currently are simple mastectomies that remove the ducts, the lobes, and the breast tissue.  I would assume that your pathology on the removed tissue from your reduction is serving as your biopsy unless they find some other locations they want to biopsy specifically, or find issues bi-laterally in your MRI.  Good luck!  If posts on this thread prompt more questions, please ask them.

Hi Pollyanna,

I hope my situation helps to answer your question. I had bleeding from the right nipple and after mammograms and ultrasounds they thought it was intraductal papilloma. After an ultrasound guided biopsy it turned out to be DCIS. I want to stress the importance of advocating for yourself. My doc (at the time, I switched later because she was completely dismissive of what I was telling her) wanted these 2 pea size lumps next to each other to be biopsied. I asked the radiologist about a much bigger lump behind the nipple. He finally agreed to biopsy it. Both were DCIS. The doc thought the area was 3 cm and therefore I could do a lumpectomy.  In reality it was almost 6 cm.  I tried to explain that an additional site was tested and that the DCIS was much bigger than she thought. I also pushed to get an MRI of the left side. The left biopsy showed PASH and some other atypical cells but not cancer. 

So at this point I was Stage 0 DCIS, grade 2. I had the bilateral mastectomy on 4/18. The pathology found 2 small areas of invasive cells (IDC?) so now I am Stage 1. It was only until after all the breast tissue got taken out and looked at that they determined I had infiltrating cancer. They didn't find it in the original biopsy (it was small and near the skin and not near where they biopsied). 

Hope my response wasn't too confusing. I now have to wait a couple of weeks to find out what the treatment plan is. How ironic that I had both breasts taken out thinking it would eliminate or at least drastically cut down on having to worry about anything in the near future. But I am grateful that they found the cancer and I can deal with it and fight it. 

Good luck to you.  

seanie, are you saying that all lumpectomies only showed DCIS and you ended up with positive nodes?  You must have had more than DCIS.  Maybe invasive was there but not discovered.

seanie,

DCIS that remains DCIS, cannot "move" as you put. It has to undergo a change, on a cellular level, to move outside the ducts. Then, of course, it is no longer DCIS. So,these are not just escaped DCIS cells, they are cells that have undergone a fundamental change which allows them to infiltrate beyond the duct.

Some surgeons are willing to use the dye pre-MX to locate the sentinel nodes then mark them (with something like a titanium marker) so they can be taken later if an invasive component is found in the MX pathology.  The only issue with this approach is if something is missed in the pathology report AND the lymph nodes have been affected.  I had DCIS with only 2 nodes taken, and I have had early lymphedema issues.  I wish I'd had them marked instead since this is a lifelong problem I have to manage now.  I was told that there was only a 2% chance of getting any sort of LE problem with only two nodes taken, but I think that is nonsense.