Table 16. Residual Tumor (R)a

Carcinoma and Carcinoid
R0Complete resection, margins histologically negative; no residual tumor left after resection.
R1Incomplete resection, margins histologically involved, microscopic tumor remains after resection of gross disease (relevant to resection margins that are microscopically involved by tumor).
R2Incomplete resection, margins involved or gross disease remains.

aReprinted with permission from AJCC: Appendix. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 133-41.

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