i'm confused since insitu is stage 0 but 11 cm is some MONSTER - it could hardly be that large and still be confined in the location where the cell changes began - which is what in situ means ductal carcinoma in situ...

perhaps it's a typo or i don't fully realize your question or situation but would also offer while appropriate to not have met an oncologist yet - i hope you've met with the cancer surgeon doing the surgery in 4 days

at any rate, i did a quick paste to better explain the tumor size & in situ vs invasive

apologies in advance if i've misunderstood your question & subsequent post
-------------------------------------------------------------------

An 11 cm tumor would be extremely large for an in situ condition. Let me explain:

In situ refers to a stage of cancer where abnormal cells are present only in the tissue where they originated and have not spread to nearby tissues or organs1. It is considered the earliest form of cancer and is classified as stage 01.
Ductal carcinoma in situ (DCIS) is a common example. In DCIS, abnormal cells are found inside a milk duct in the breast. It is noninvasive, meaning it hasn’t spread beyond the duct and has a low risk of becoming invasive2.
Tumor size is part of breast cancer staging. In the TNM staging system, a “T” followed by a number indicates the size of the tumor. However, an 11 cm tumor would be unusual for an in situ condition. Such a large tumor would likely be classified as invasive rather than in situ.
Diagnosis and treatment for DCIS typically involve breast imaging (such as mammograms), biopsies, and surgical options like lumpectomy or mastectomy3.
If you suspect any changes in your breasts, such as a lump or unusual skin appearance, I recommend consulting a doctor promptly for evaluation and appropriate screening2. Remember that early detection is crucial for effective management.

***wanted to name source - thinking 'verywellhealth' but mayo + 3 others also listed the same data

I saw my surgeon first. It made the process move faster. I had a double mastectomy stage 1. Everything in my breasts were biopsied. When I saw my oncologist we discussed my treatment plan.

I wouldn't but that is just me.