Table 5. HPV association. IL: ipsilateral. BL: bilateral. PE: panendoscopy. Ix: Investigation. Ex: examination. BOT: base of tongue, PT: palatine tonsillectomy, TBM: tongue base mucosectomy
Diagnostic Procedures for the Tongue Base
Table 6 shows the eight studies which specifically look at the approach to the tongue base29-36. Typically these patients have already undergone a negative tonsillectomy or have palatine tonsillectomy and tongue base sampling performed at the same time.
A variety of surgical techniques have been used in these studies, including frozen sections, used as a decision node for simultaneous palatine tonsil and tongue base procedures under one anaesthetic. Overall, there is a lack of high quality evidence. The studies are mainly retrospective and heterogenous in terms of workup. However, the majority have had PETCT, EUA and biopsies, and often, where appropriate, negative tonsillectomy prior to tongue base mucosectomy (TBM).
The detection rate for tongue base mucosectomy ranged from 1329-90%36. This is higher than the pickup rates for random biopsies of 011-18%5 (table 1.1), suggesting TBM is more effective than deep tissue biopsies.
There is variable practice with regard to approach to the contralateral tongue base (table 5) but contralateral and/or synchronous rates is reported in several studies. The rate of contralateral tongue base SCC primaries ranged from 029,32-12%33(table 6). Durmus et al37 had an overall bilateral rate of 17.6% with palatine tonsil rate of 66% and lingual tonsil rate of 33%4037 using TORS (table 7).
Across the studies included in this systemic review TBM haemorrhage rates ranged between 032-8.5%38(table 6 and 7) most of which were managed conservatively. These include alternative techniques.
HPV/P16 positivity rate was reported in many of these studies (table 6 and 7). There was a high rate of HPV positive cancers in those patients with positive TBM. Several studies reported rates of up to HPV 100% positivity for those with a tongue base primary32,34,35 As with tonsillar primaries, HPV positivity should prompt meticulous investigation of the oropharynx.