Question: Do I need an axillary lymph node dissection if I have in situ or early-stage invasive breast cancer?
Answer: If you have in situ cancer, you do not need an axillary lymph node sampling, dissection or even a sentinal lymph node biopsy. The reason is that in situ cancer is not invasive and it really cannot spread to the axilla.
Now with that said, let me tell you that if an in situ cancer is big enough to merit a mastectomy, I routinely do a sentinal node biopsy and take one or two lymph nodes from the bottom of the axilla. The reason I do this is because the larger the in situ cancer is, the more likely we are to find invasive cancer when we thoroughly evaluate it. Remember, most of these lesions are diagnosed with a needle. So we only have a tiny sampling of what we think the lesion is. So a needle biopsy that shows in situ cancer has a reasonable potential maybe 10 to 20 percent of showing an invasion when we serially section and evaluate it.