- The margins of the resected specimen must be histologically free of invasive tumor and ductal carcinoma in situ (DCIS). For patients in whom pathologic examination demonstrates tumor present at the line of resection, additional operative procedures may be performed to obtain clear margins. This is permissible even if axillary dissection has been performed. Patients in whom tumor is still present at the resected margins after re-excision(s) must undergo total mastectomy to be eligible.