Dear BCInfoseeker, DCIS (ductal carcinoma in situ) means that the cells are confined to the duct and have not invaded the lining of the duct, thus would not have spread to the lymph nodes, so lymph nodes are not tested when no evidence of invasive cancer is present.
It's practically impossible with DCIS that lymph nodes would have tumor in them: the "IS" part of DCIS stands for in-situ, which means non invasive, not having crossed the membranes that separate the lining of the ducts from blood vessels and lymph nodes. So when there's DCIS only, most people would not recommend lymph node sampling. It's not considered necessary. Pretty much by definition, they're ok.