time between your last mammogram and your DCIS diagnosis?

I skipped about 3 years worth of mammograms until my mother was diagnosed which prompted me to go in.   I had gone at 40 and 41 and then not again until 45.   They found a very small amount of grade  2 (but with necrosis) DCIS as well as an even smaller amount of IDC.     No idea if it would have been picked up had I gone in a year prior, but I tend to doubt it as it was so small.    I'm just glad I went in when I did as I might have waited a few more years had my mom not been diagnosed since they had recently changed the recommendation to not needing annual ones until age 50.

Research on the development of DCIS suggests that DCIS does not usually progress from low grade to intermediate to high grade.  DCIS can develop directly as high grade. 

LilyLuv - They suspected they saw microcalcifications during my annual mammogram which is part of my physical for work.  Got called back for a second mammogram for verification, then stereotactic biopsy (when they diagnosed the multifocal DCIS, grade 3), which led to an excisional biopsy (where they discovered LCIS and ALH), and then I opted for a BMX.  There was no indication of anything on the mammogram from the prior year.

I've always wondered about this, too.

Microcalcifications were seen on my annual mammogram in October 2012 and the nurse called my home and told me about them, said to not worry, but they wanted me to have a follow up on my left breast in April 2013 with magnifications.  I had that and no one was concerned.  The nurse called again and said that I should then go back to my yearly mammograms of both breasts in October of 2013.   Now, that's when all of this began, because the very next day, my PCP called, very concerned, and said that the microcalcs were now clustering in a pattern and MUST be biopsies.  Her attitude, of course, worried me, but I also wondered how something could go from April with magnifications and no real concern to October with (what I believe was probably Birad 4) and become cancerous.  

I had the biopsy reluctantly - still believing they were over-reacting, possibly because of my high risk status with my mother having had BC in 1978 and my sister on her second bout.  I didn't get totally stressed out until I hadnt heard for a week and called the office and was told to come to talk to doctor the next morning at 8. The doctor was very serious and concerned and told me that the biopsy had found DCIS, high grade with necrosis.  I was still more optimistic than she, saying "Well it's early stage, and treatable, right?"  I still could not wrap my head around it having developed within those 6 months.

Being high grade, this is probably how and why it became so apparent in October when it was not in April.  I've asked several doctors since if it was not there in April or if the radiologist in April just made the wrong call.  Of course, no one can tell me.  I've also wondered how the DCIS itself pops up.  Does it begin as one of the pre pre cancers?  When you see the high grade pictures, with the duct stuffed with cells and the holes in it, does it look six months previously (maybe before it throws off the microcalcs) as a partially filled version of it's later-stage self?   Or does it transform quickly into what it becomes?  Pathologists, when examining tissue must see - either only high grade DCIS as we know and see it or partial-looking high grade DCIS.  These may be rhetorical questions!

But I would say to answer your question, that since my DCIS was being watched closely (with magnifications) a mere 6 months earlier, that it was active during those six months and hadn't been lurking around for much longer than a year or so.  

Just because a mammogram is clear doesn't mean that the DCIS didn't started to develop much earlier.  The calcifications are not the DCIS - the calcs are formed from the dead DCIS cells.  Here's how breastcancer.org explain it:

DCIS is usually found by mammography. As old cancer cells die off and
pile up, tiny specks of calcium (called "calcifications" or
"microcalcifications") form within the broken-down cells. The mammogram
will show the cancer cells inside the ducts as a cluster of these
microcalcifications, which appear either as white specks or as a shadow. Diagnosis of DCIS

Breast cancer normally starts as just a few cells, which might multiply quickly, or might multiply slowly or might remain dormant for a while. With DCIS (or any cancer), it could be years before enough cancer cells have died and formed calcifications that are large enough to be visible on a mammogram.  Consider that autopsy studies have found that on average, ~9% of women who die have undetected DCIS - and interestingly, "Prevalences were higher among women likely to have been screened (that is, women 40 to 70 years of age)."  So these women had DCIS that didn't show up on their mammograms.  They never knew they had DCIS and they passed away of some other condition.  Would some or most of these cases of DCIS eventually have been found?  Probably but who knows how many years it might take before those first calcifications finally showed up on a mammogram. 

Using Autopsy Series To Estimate the Disease “Reservoir” for Ductal Carcinoma in Situ of the Breast: How Much More Breast Cancer Can We Find?

I believe like all cancers, DCIS forms one cell at a time. Each cell splits, and then splits again and that's how eventually DCIS can completely fill a duct and/or be quite spread out within the ductal system.

Hi Mayanne, I hope you are doing well.  I don't have the scientific answer, but I did have the pre-pre cancer cells next to the DCIS.  I had atypical ductal hyperplasia, and it was categorized as "severe", so I believe that the DCIS evolves from that previous stage, and the severely atypical ductal hyperplasia can lead to high grade DCIS, which I had.  At the same time, I will state that 17 years earlier, they also found severe atypia (atypical ductal and lobular hyperplasia), and despite several intervening biopsies (all surgical), the DCIS wasn't found until much later.  It's quite possible that the first batch of atypical cells did not contribute to the later diagnosis at all, and given that the biopsy was surgical, they could have been removed at that time.  Then, the body produced more of those cells, but now I'm older, and the older one gets, the more chance that the cells will progress.  My view of this is that my body (immune system, etc.) has actually prevented the cells from progressing further.  As a result, I had a fairly large amount of multifocal high grade DCIS (probably close to 6 cm), but it was all pure DCIS.  I will say that the mammo only showed a very small portion of the calcifications and the pathology that was ultimately found.

Mayanne, good luck with the radiation treatments, and I hope it isn't too too difficult to get there daily, given the challenging winter we've been having (way worse up there, I know).