DCIS with >10 areas of microinvasion

10+ microinvasions is certainly unusual. But a microinvasion is at most 1mm in size. The 6mm IDC tumor trumps the microinvasions and trumps the DCIS. Your diagnosis and treatment plan will be based on that 6mm invasive tumor; the microinvasions and DCIS will be satisfactorily treated by whatever is done to address this larger tumor. Your staging will be based on only the size of the largest IDC tumor, which in your case is 6mm. The micro invasions are not added into the size, and the size of the DCIS is ignored completely.

Although there are separate Oncotype tests for DCIS and for IDC, only patients who have pure DCIS are eligible for the DCIS Oncotype, which assesses the need for and benefit of radiation. The invasive cancer Oncotype, which assesses the need for and benefit of chemo, would be used in your case, and does not look at the DCIS component. The invasive cancer Oncotype test analyzes 21 genes within the tumor. It does not incorporate the size of the tumor into the scoring. Your test will be done on the tissue from the 6mm tumor.

The only way that the DCIS would come into play when a tumor includes both DCIS and IDC is in consideration of the surgery, if the DCIS is near the margins or is widespread and as a result necessitiates either a re-excision or a MX.