PET in the evaluation of head and neck cancer treatment - management of the neck

Abstract: The treatment for head and neck squamous cell carcinoma (HNSCC) is surgery or (chemo)radiotherapy +/- surgery. Side effects related to therapy are long lasting and adversely affects quality of life. The incidence of oropharyngeal cancer is increasing and patients commonly present an advanced tumour stage with neck metastases at the time of diagnosis. The treatment protocol previously comprised radical (chemo)radiotherapy and surgery i.e., neck dissection. However, persistent tumour cells after (chemo)radiotherapy are found in only 20-30% of the neck specimens and a systemic neck dissection have therefore been questioned.
The general aim of the present thesis was to explore if positron emission tomography (PET) could be used for radiotherapy response evaluation and adequately determine the need for further therapeutic interventions in patients with HNSCC treated with curative intent. The overall clinical goal with the thesis was to reduce the treatment related morbidity by avoiding unnecessary neck dissection without risking an increase in failures.
In studies I and III we evaluated the performance of PET as a tool for assessment of therapy response and the consequences of omitting neck dissections in patients with a complete metabolic response after treatment. Study II focused on therapy response evaluation of the primary site. Lastly, study IV evaluated three different methods for interpreting PET scans in head and neck cancer patients.
In conclusion, neither nodal control nor survival is compromised by omitting neck dissection in patients with a complete metabolic response after therapy. A physical examination, preferably supported with a PET scan, is feasible and sufficient for an evaluation of the primary site response. Qualitative interpretation with visual inspection of PET scans is a satisfactory method to assess tumour metabolism and the use of a 5-point Likert scale is a promising tool to reduce the number of scans judged as equivocal to a minimum.