Head & neck: Oropharynx — HPV/p16 TNM8 staging

Why B is correct

In the TNM9 clinical classification for p16-positive oropharyngeal cancer (the size/laterality-based cN1/cN2/cN3 categories are retained from TNM8, though TNM9 now raises the cN category by one level when imaging-detected extranodal extension (iENE) is present, which is absent here), ipsilateral nodes (single or multiple) none larger than 6 cm are all classified as cN1; nodal number no longer affects the N category as it does in p16-negative disease. A T2 N1 p16-positive tumour falls into overall stage I, reflecting the favourable prognosis of HPV-associated disease.

And why the others are not

• AWrong — the N category is correct as cN1, but T2 N1 p16-positive disease is stage I, not stage II (stage II requires T0-T2 N2 or T3 N0-N2).
• CWrong — cN3b requires clinical extranodal extension, which is absent here.
• DWrong — there is no cN2 stage III combination producing this result for p16-positive disease; ipsilateral sub-6 cm nodes are cN1.
• EWrong — N2b (multiple ipsilateral nodes) and stage IVA belong to the p16-negative classification, not the p16-positive clinical staging.

Source AJCC 8th edition staging of oropharyngeal cancer by HPV/p16 status — review — Lydiatt WM, Patel SG, O'Sullivan B, et al. AJCC Cancer Staging Manual, 8th edition (2017); reviewed in Eur Arch Otorhinolaryngol 2020. PMC7410862.