Table 12. Primary Tumor (T)a,b

TXPrimary tumor cannot be assessed.
T0No evidence of primary tumor.
T1Tumor ≤2 cm in greatest dimension.
T1aTumor ≤1 cm in greatest dimension.
T1bTumor >1 cm but not >2 cm.
T2Tumor >2cm but not >4 cm or with extension to the cecum.
T3Tumor >4 cm or with extension to the ileum.
T4Tumor directly invades other adjacent organs or structures, e.g., abdominal wall and skeletal muscle.c

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.

bTumor that is adherent to other organs or structures, grossly, is classified cT4. However, if no tumor is present in the adhesion, microscopically, the classification should be classified pT1–3 depending on the anatomical depth of wall invasion.

cPenetration of the mesoappendix does not seem to be as important a prognostic factor as the size of the primary tumor and is not separately categorized.

From: Gastrointestinal Carcinoid Tumors Treatment (PDQ®)

Cover of PDQ Cancer Information Summaries
PDQ Cancer Information Summaries [Internet].
Bethesda (MD): National Cancer Institute (US); 2002-.

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