Guinea pigs, are we ?

After a routine mammogram detected my 2.2 cm IDC, I had an MRI before a lumpectomy. My surgeon called with odd results - she said that if she didn't know better, the MRI showed that there was no cancer in the breast. I thought that was good - she wasn't so sure. I had a lumpectomy with dirty margins (DCIS in 2 ducts), another lumpectomy (which turned up another .7 cm IDC and more DCIS), then a mastectomy (only a few residual cancerous cells left in the cavity.) My onc said that about 2% of tumors don't show up on MRI.

The 3D ultrasound sounds promising ( and much less painful and nerve-wracking than a mammo or MRI.)

 Yes, not all dcis will become invasive because not all dcis are alike. Lower grade cancer cells take longer (even a life time) to become troublesome, or invasive. From what I learned about dcis is that the grade 3, high grade cells are more likely to become invasive. The high grade cancer cells do not look like normal cells. The high grade cells that becomes solid must either burst from the ducts or travel up or down the ducts. The person dx with high grade dcis is at high risk for invasive cancer. It is a matter of time no matter what age they are.  

Basically, those who have lower grade dcis are the ones in question to whom will or will not be dx with invasive cancer. High grade dcis is a sure thing that is if it is left alone.

From BCO

Grade I (low grade) or Grade II (moderate grade)

Grade I or low-grade DCIS cells look very similar to normal cells or atypical ductal hyperplasia cells. Grade II or moderate-grade DCIS cells grow faster than normal cells and look less like them. Grade I and Grade II DCIS tend to grow slowly and are sometimes described as "non-comedo" DCIS. The term non-comedo means that there are not many dead cancer cells in the tumor. This shows that the cancer is growing slowly, because there is enough nourishment to feed all of the cells. When a tumor grows quickly, some of its cells begin to die off.

People with low-grade DCIS are at increased risk of developing invasive breast cancer in the future (after 5 years), compared to people without DCIS. Compared to people with high-grade DCIS, however, people with low-grade DCIS are less likely to have the cancer return or have a new cancer develop. If more cancer does develop, it typically takes longer for this to happen in cases of low-grade DCIS versus high-grade.

Grade III (high-grade) DCIS

In the high-grade pattern, DCIS cells tend to grow more quickly and look much different from normal, healthy breast cells. People with high-grade DCIS have a higher risk of invasive cancer, either when the DCIS is diagnosed or at some point in the future. They also have an increased risk of the cancer coming back earlier - within the first 5 years rather than after 5 years.