R1

**Semantic type:** Finding

**Definition:** Presence of microscopic residual tumor after treatment.

**Synonyms:** - Microscopic Residual Tumor - R1 - Complete Resection, Positive Margins - R1 - Complete Resection, Positive Margins - R1 - Complete Resection, Positive Margins - Microscopically Positive - R1: Microscopic residual tumor - R1: Microscopic residual tumor. No gross residual disease but positive microscopic margins.