- Negative, or close but negative, inked histologic margins of tylectomy or reexcision specimen to be confirmed prior to placing the brachytherapy catheters. Margins generally are positive if there is invasive or noninvasive tumor at the inked resection margin, close but negative if the tumor is within 2 mm of the inked margin and negative if the tumor is at least 2 mm away from the inked edge.