Overall, the evidence showed that recurrence rates and overall mortality for fluorodeoxyglucose positron emission tomography (FDG PET)-CT-guided management after radical chemoradiotherapy were similar to those for neck dissection. In addition, the evidence showed that FDG PET-CT was cost-saving compared with neck dissection, and would prevent unnecessary surgeries, surgical complications, and adverse events.
The committee agreed to make recommendations only for people with oropharyngeal, laryngeal and hypopharyngeal primary sites, because these were the main focus of the evidence. Most of the people in the study had an oropharyngeal primary site and more than 1 positive node under 6 cm across in the neck, and the evidence was strongest for this population. Therefore, the committee agreed that they should be offered an FDG PET-CT scan.
The evidence was weaker for people with:
an oropharyngeal primary site and 'N2a' stage disease (only 1 positive node of more than 3 cm but no more than 6 cm across)
an oropharyngeal primary site and higher 'N' stage disease (1 or more positive node larger than 6 cm across in the neck)
laryngeal or hypopharyngeal primary sites.
To reflect this, FDG PET-CT scanning could be considered for these groups.
The evidence did not include people with an oropharyngeal primary site and 'N1' stage disease (only 1 positive node of less than 3 cm across). However, the committee agreed that it is particularly important that FDG PET-CT scans are considered for this population to avoid unnecessary surgery. These people are likely to be at a lower risk of recurrence and so the benefits of neck dissection are lower.
The committee noted that new classifications for head and neck cancer (TNM classification of malignant tumours, 8th edition) have been introduced, which are different from those used in the evidence. They decided to describe the stage of cancer for these recommendations in terms of the number and size of positive nodes to avoid confusion.
The timing of FDG PET-CT scans (3 to 6 months after completion of radical chemoradiotherapy) is in line with current Royal College of Radiologists guidelines. Scans earlier than 3 months are more likely to give a false-positive result, due to the residual effects of treatment.
The committee decided to be specific that neck dissection should not be offered to people with no abnormal FDG uptake or residual soft tissue mass, to give clear advice about how to interpret a 'negative' FDG PET-CT result.
The committee noted several areas in which future research would be helpful, such as management for people with indeterminate test results (see research recommendations 1 and 2), the role of FDG PET-CT for people with nasopharyngeal cancer (see research recommendation 3) and the effectiveness of FDG PET-CT to guide follow-up (see research recommendation 4).
There may an increase in the number of FDG PET-CT scans performed and a reduction in surgical procedures. However, the evidence showed that the amount of money saved from unnecessary surgery is likely to be considerably higher than the cost of the additional scans.
Full details of the evidence and the committee's discussion are in evidence review A: Evidence reviews for treatment of advanced disease.