R1 resection
Surgical resection where cancer cells are present at the microscopic margin, indicating incomplete tumor removal.
Full Definition
An R1 resection refers to a surgical procedure where the primary tumor has been removed but cancer cells remain at the microscopic resection margin, as determined by pathological examination. This finding indicates that the tumor removal was incomplete at the cellular level, even though no gross residual disease is visible to the surgeon. R1 status significantly impacts prognosis and often necessitates additional treatment such as re-excision, radiation therapy, or systemic therapy. The R classification system (R0, R1, R2) is crucial for oncologic surgical planning and patient counseling.
Usage
Usage note: Always specify whether referring to microscopic (R1) versus macroscopic (R2) residual disease for clarity.
In Context
- "The pathology report confirmed R1 resection with tumor cells present at the anterior margin." — Surgical pathology report
- "Given the R1 resection status, the multidisciplinary team recommended adjuvant radiation therapy." — Treatment planning document