Unknown primary tumors of the head and neck (staging)
Unknown primary tumors of the head and neck staging refers to TNM staging of metastatic carcinomas in the head and neck region without an identifiable primary tumor. The typical scenario involves squamous cell carcinoma present in a cervical lymph node, no obvious primary source on clinical examination and imaging, and negative testing for both Epstein Barr virus (EBV) and human papillomavirus (HPV), which would otherwise be categorized as a T0 nasopharyngeal cancer or oropharyngeal (p16+) cancer, respectively. The following article reflects the 8th edition manual published by the American Joint Committee on Cancer (AJCC), which is used for staging starting January 1, 2018 1,2.
Primary tumor (T)
By definition, an occult primary tumor is designated T0 (no evidence of primary tumor).
Regional lymph node (N)
Regional nodal status is defined the same as for most other cancers of the head and neck. See the main article, cervical lymph node (staging).
Distant metastases (M)
The terms pM0 and MX are not valid TNM categories. The following categories may be used:
- cM0: no evidence of metastases
- cM1: distant metastasis
- pM1: distant metastasis, microscopically confirmed
- T0, N1, M0
- T0, N2, M0
- T0, N3, M0
- T0, [Any N], M1
Changes from prior version
This staging system is new in the 8th edition, concurrent with elimination of the T0 category of each of the head and neck primary sites from the 7th edition except the HPV- and EBV-associated cancers. Salivary gland cancers also retain a T0 category due to their uniquely identifiable histology.
- 1. Amin MB, Edge SB, Greene FL, et al. AJCC Cancer Staging Manual. (2018) ISBN: 9783319406176
- 2. American College of Surgeons. AJCC Cancer Staging Form Supplement. AJCC Cancer Staging Manual, Eighth Edition. 5 Jun 2018. Available at cancerstaging.org
- 3. Lydiatt WM, Patel SG, O'Sullivan B, Brandwein MS, Ridge JA, Migliacci JC, Loomis AM, Shah JP. Head and Neck cancers-major changes in the American Joint Committee on cancer eighth edition cancer staging manual. (2017) CA: a cancer journal for clinicians. 67 (2): 122-137. doi:10.3322/caac.21389 - Pubmed