Table 1.

Comparison of AJCC 7th edition and AJCC 8th edition T category (primary tumor) criteria^a,b.

	8th Edition (implemented 2018)		7th Edition (implemented 2010)
T Category	Thickness	Ulceration status	Thickness	Ulceration status
TX	N/A	N/A	N/A	N/A
T0	N/A	N/A	N/A	N/A
Tis	N/A	N/A	N/A	N/A
T1	≤1.0 mm	Unknown or unspecified	≤1.0 mm	Unknown or unspecified
T1a	<0.8 mm	Without ulceration	≤1.0 mm	Without ulceration and <1 mitosis/mm2
T1b	<0.8 mm	With ulceration	≤1.0 mm	With ulceration or ≥1 mitosis/mm2
	0.8–1.0 mm	With or without ulceration
T2	>1.0–2.0 mm	Unknown or unspecified	1.01–2.00 mm	Unknown or unspecified
T2a	>1.0–2.0 mm	Without ulceration	1.01–2.00 mm	Without ulceration
T2b	>1.0–2.0 mm	With ulceration	1.01–2.00 mm	With ulceration
T3	>2.0–4.0 mm	Unknown or unspecified	2.01–4.00 mm	Unknown or unspecified
T3a	>2.0–4.0 mm	Without ulceration	2.01–4.00 mm	Without ulceration
T3b	>2.0–4.0 mm	With ulceration	2.01–4.00 mm	With ulceration
T4	>4.0 mm	Unknown or unspecified	>4.00 mm	Unknown or unspecified
T4a	>4.0 mm	Without ulceration	>4.00 mm	Without ulceration
T4b	>4.0 mm	With ulceration	>4.00 mm	With ulceration

N/A, not applicable; TX, primary tumor thickness cannot be assessed (e.g. diagnosis by curettage); T0, no evidence of primary tumor (e.g. unknown primary or completely regressed melanoma); Tis, melanoma in situ.

^aAdapted from and used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, 8th Edition (2017), published by Springer International Publishing (Gershenwald JE, Scolyer RA, Hess KR, et al. Melanoma of the Skin. In: Amin AB, Edge SB, Greene, FL, et al. (Eds). AJCC Cancer Staging Manual. 8th Ed. New York: Springer; 2017:563–585).

^bAdapted from and used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, 7th Edition (2009), published by Springer Verlag (Balch CM, Gershenwald JE, Soong SJ, et al. Melanoma of the Skin. In: Edge SB, Byrd D, Compton C, et al. (Eds). AJCC Cancer Staging Manual. 7th Ed. New York: Springer; 2009: 325–344).