insights anyone?

Js, my situation was kind of similar - I had a solid tumor with a cyst attached to it. Overall, the tumor plus cyst was 3.5 cm. The difference is that I had a VAD biopsy which took pretty big hunks out of the tumor and cyst. That totally deflated the cyst part and it didn't refill. There is nothing on my biopsy report about the fluid that was vacuumed out so I don't know if there were cancer cells in the fluid. When the lump was removed, part of the solid part was DCIS, part was IDC, and the remaining wall of the cyst was benign. The IDC part was 0.9 cm. But it is possible that it was bigger before the VAD took hunks out of it and it is possible that part of the cyst wall that was taken out had cancer cells - especially since the path for the VAD was chosen to take the most suspicious parts of the lump. 

Tumor size is always an approximation anyway - they are looking at the longest dimension rather than the volume of the tumor. A long skinny tumor could have the same "size" as a round ball shaped one. Anything between 2 cm and 5 cm with negative nodes makes it stage IIa. If it was between 1 and 2 cm it would be stage Ic.

In any case, I don't think this makes much difference for your treatment decisions so you don't need to focus on it too much. It is more important that your tumor is hormone positive and HER2- (both are good factors) and that it is Grade 3. The NCCN practice guidelines for breast cancer take the same path for any tumor over 1 cm (and even for any tumor between 0.6 and 1 cm with unfavorable features which includes grade 3). 

Another factor is the results of the oncotype. Grade is one way of determining how aggressive cancer cells are. It is done by looking at features of the cells under a microscope to see if they are more close to regular cells or more different. It is a somewhat subjective measurement. Oncotype isa another way of determining how aggressive the cancer cells are. It looks at the genes in the cancer cell to see how many are present that lead to aggressive growth. A score less than 18 says that recurrence risk is low and hormone therapy should be enough. Above 31 says that recurrence risk is high and you should probably have chemo. Between those two numbers is intermediate risk and a gray area for chemo (there is a clinical trial underway to see what the outcomes are for chemo vs no chemo in this range).

I hope that your oncologist or surgeon has ordered the oncotype test. 

Bluedasher, I am curious as to why they only do the oncotype testing with HER2 negative tumors.  I have read that it is because with HER2 + tumors,  the number would always show up high enough to warrant chemo anyways, so why bother.  It still seems like it might be a valuable number to have.  Do you know anymore about why they don't do it on all tumors? 

Like mmm said - it would just be a waste of money. The OncoType test is to help you decide if you need chemo or not. If you are HER2+, you already know that recurrence risk is high without chemo. I don't think Oncotype says anything about recurrence risk after chemo and Herceptin so the number wouldn't be meaningful.