Understanding Your Breast Cancer Diagnosis: 1.5mm Invasion & Lymph Node Biopsy

Question
Thank you in advance. I am a 61 year old female originally diagnosed with DCIS almost 2 months ago. Had removal of breast tissue 3 weeks ago and pathology came back indicating breast cancer. The surgeon said '1.5 mm'. I'm assuming he means invasion of 1.5 mm (IDC)- would this be right? I am scheduled for a lymph node biopsy in 1 week and am wondering the likelihood of positive nodes? and of avoiding chemo? I should mention there is a family history of breast Cancer ( 2 younger sisters).

Answer
If the diagnosis really was DCIS it was a cancer in situ (= "cancer in the site of origin") or cancer stage 0. In that case he can hardly have meant an invasion of 1.5 mm since a cancer in situ is NOT invading - in fact that is the definition of a cancer in situ! What he may have meant was the size of your lesion which is possible if a cancer in situ is found by microscopy in an otherwise benign lesion that has been surgically removed. If so it is rather unlikely that anything will be found by your sentinel lymph node biopsy but it should anyway be done to be on the safe side. If nothing is found chemotherapy is not necessary BUT I DO recommend radiation therapy of the breast from which your lesion was removed - especially so with your family history! That is the standard treatment based on experience! Good luck!

In that case it is no longer a cancer in situ but may be an invading cancer. In that case the invasion may indeed be 1.5 mm and the sentinel node biopsy becomes even more important. So will your radiation therapy of your breast be. And if there is any cancer in that node then chemotherapy will also be important as may hormonal therapy be if there are any hormonal receptors in your tumor.