Unknown/Occult Primary Cancers (CUP) of Head & Neck: Treatment strategies for potential primary sites (SCC)

CONTROVERSIAL
No prospective randomised studies; many studies are pre-Intensity Modulated Radiotherapy (IMRT)
Many (70-80%) never manifest primary cancer (possibly as primary is irradiated with the nodes?)
Upfront RT of potential primary sites
- Could compromise future treatment of 2nd primaries
- Treatment must be individualised: Consider performance status, social circumstances, N-staging when deciding what to treat (how large will RT fields be if potential primary site is included vs patient’s ability to tolerate treatment?)
- Even with IMRT it is impossible to completely spare ipsilateral oropharynx when Level 2 treated (majority of patients)
- Therefore, may be sensible to treat ipsilateral tonsil/tonsillar pillars, ipsilateral BOT (not whole oropharynx) to a moderate dose, rather than have a partial/inhomogeneous dose to ipsilateral oropharynx
- May also be sensible to treat oropharynx if patient unlikely to attend regular follow-up
Empiric radiation to nasopharynx is not recommended
- Significant toxicity/morbidity
- Some distance from nodal areas; so is easy to exclude even when treating large neck node masses
- Consequently, relatively easy to treat later if a primary tumour should manifest in the nasopharynx
Positive tumour markers are not absolute indications to treat oropharynx (p16) or nasopharynx (EBV) – rather, they may indicate where best to focus clinical examination, biopsies and imaging