Evaluation of Unknown/Occult Primary Cancers (CUP) of the Head & Neck: Key points

Defined as lymphatic or haematogenous metastases to cervical nodes but unable to identify primary tumour
- Primary tumour subsequently appears in 20-30% (similar to expected rate of 2nd primaries)
  Remainder remain undetected possibly due to small size, hidden location (e.g. tonsillar crypts), slow growth, spontaneous involution or having been irradiated
Squamous cell cancer (SCC)
- Most cases, especially when nodes located in levels 1-3
- 90% are HPV-associated oropharyngeal SCC (may not be true in Africa)
- Additional markers done on FNAC or biopsy of node
  - EBV points to nasopharynx carcinoma (NPC) – but some lymphomas are EBV (+) : an excision biopsy may be needed
  - P16+ points to oropharyngeal carcinoma, but may also occur with NPC, skin and oral cavity SCC
- Treatment
  - Can be treated with curative intent
  - Neck: Neck dissection and/or CRT
  - Potential primary sites (nasopharynx, oropharynx)
    - Insufficient data and hence controversial whether to irradiate, and may have significant long-term morbidity
    - If 2-D or 3-D conformal radiation only, then consider including oropharynx when radiating the neck
    - If IMRT available, then one may elect to watch-and-wait whether primary appears
Level 4/5 nodes
- Mainly adenocarcinomas from below clavicles (lung, breast, colon, prostate, OG junction, stomach, pancreas)
- SCC from oesophagus, lung, skin
When interpreting FNAC results, also consider lymphoma, melanoma, thyroid carcinoma