Lessons from a standardized program using PET–CT to avoid neck dissection after primary radiotherapy for N2 squamous cell carcinoma of the oropharynx

• This is one of the few prospective studies of using a 12-week PET–CT to determine the need for neck dissection.
• We limit our study to N2 disease where the question is most relevant.
• We demonstrate late recurrences after an interval of negative imaging.

SummaryObjectivesTo report the results of a standardized program using positron emission tomography (PET)–computed tomography (CT) approximately 12 weeks after primary radiotherapy to determine the need for a planned neck dissection in patients with radiographic N2 squamous cell carcinoma (SCC) of the oropharynx.MethodsFifty consecutive patients with T1–4 and hemineck radiographic stage N2A–B SCC of the oropharynx for whom the only indication for planned neck dissection was a positive PET–CT performed ∼12 weeks after completing primary treatment with radiotherapy.ResultsResults of PET–CT to identify residual neck disease were as follows: sensitivity and positive predictive value, 0%; specificity, 89%; negative predictive value, 91%; potential neck recurrence from using this 12-week PET–CT program, 2%. The time between negative PET–CT and detection of neck recurrence was 0.5, 0.6, 1.2, and 2.0 years. The rate of successful (>1 year) salvage of neck recurrence was 25% (1/4).ConclusionsPET–CT approximately 12 weeks after radiotherapy for oropharyngeal cancer is an excellent way to identify patients who do not need neck dissection. Approximately half of neck recurrences present over 1 year after negative PET–CT and the chance of successful salvage is low.