Table 2.

Summary comparing 7^th and 8^th ed. AJCC staging of OCSCC and OPSCC.¹⁰

Change	7th Ed. (2010)	8th Ed. (2017)
		Oral Cavity	Oropharynx (p16-negative)	Oropharynx (p16-positive)
T-Classification	TX: primary tumor cannot be assessed T0: no primary Tis: carcinoma in situ T1: size ≤2 cm T2: size 2-≤4 cm T3: size >4 cm or extension to lingual surface of epiglottis T4: ○T4a: moderately advanced (extrinsic tongue muscle involvement constituted T4a) ○T4b: very advanced	T1: size ≤2 cm and DOI ≤5 mm T2: size ≤2 cm and DOI 5-≤10 mm or size 2-≤4 cm and DOI ≤10 mm T3: size >4 cm or any tumor>10 mm DOI		T0 if provenp16+ disease without evidence of primary tumor All locally advanced combined to T4
N-Classification	NX: regional node involvement cannot be assessed N0: no LN involved N1: single ipsi LN ≤3 cm in size N2: N2a: single ipsi LN, 3-≤6 cm in size N2b: multiple ipsi LNs, all ≤6 cm in size N2c: any bi or ctr LNs, all ≤6 cm in size N3: any LN >6 cm in size	Clinical
		N0–N2: same as previous and ENE(-) N3 now with subcategories: N3a: previous N3 (size >6 cm) and ENE(-) N3b: any ENE(+), either clinical or radiographic		•Previous N1, N2a, N2b combined to N1 (≤6 cm with or without ENE) •Previous N2c isN2 (≤6 cm with or without ENE)
		Pathologic
		Criteria for pathologic ENE(+): Oral cavity: only macroscopic (>2 mm) Oropharynx: micro- (≤2 mm) or macroscopic (>2 mm) N1–N2: same as previous and ENE(-) with exception: N2a includes lymph node ≤3 cm, ENE(+) LN N3 now with subcategories: N3a is previous N3 (size >6 cm) and ENE(-) N3b: ≥3 cm and ENE(+) LN or >1 ENE(+) LNs		•ENE status not incorporated •N1:≤4 LNs involved •N2: >4 LNs involved
TNM Stage Grouping	Clinical or pathological TNM used for same grouping system	Same as previous		Separate clinical and pathological TNM groupings

DOI: depth of invasion; LN: lymph node; ENE(+): extranodal extension present; ENE(-): extranodal extension absent; ipsi: ipsilateral; bi: bilateral; ctr: contralateral.