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

Index: Clinical Practice Guidelines for CUP

Resource Appropriate CUP Guideline Scenarios