What Is the Role of PET-CT in Residual Occult Nodal Disease?

PHOENIX-Just how useful are PET or PET-CT in identifying residual occult nodal disease in patients with head and neck cancer? Two presentations at the 2009 Combined Otolaryngology Spring Meeting addressed this topic. In one, researchers suggested that delaying PET-CT may work to help reduce the number of planned neck dissections. In the other, researchers said that PET-CT does have a role to play in head and neck patients, but cannot replace neck dissection as a staging tool.

Christine Gourin, MD, Associate Professor of Otolaryngology-Head and Neck Surgery at Johns Hopkins University in Baltimore, presented details of a retrospective study of patients treated for head and neck squamous cell cancer (HNSCC).

The role of PET-CT in detecting residual occult nodal disease in patients following chemoradiation is controversial, she said. Generally, what is advocated is a planned post-treatment neck dissection-regardless of clinical response to chemoradiation. Proponents of neck dissection argue that there is a high incidence of residual occult disease found in histopathological evaluations of samples from neck dissection, and that the procedure leads to better regional control rates. Opponents, however, maintain that there are low regional recurrence rates in patients with a complete response who are not treated with neck dissection, and that there is no change in survival in most patients by adding neck dissection.

The question is, can PET-CT help identify patients who could be spared unnecessary neck dissection? The combined technology provides both physiologic and anatomic information. But the efficacy of PET-CT in predicting residual nodal disease after chemoradiation, and thus the need for posttreatment neck dissection, appears dependent on the timing of imaging after chemoradiation, Dr. Gourin said. Post-treatment neck dissection is ideally performed within four to 12 weeks after chemoradiation. This study sought to determine if PET-CT findings correlated with neck dissection findings.

PET-CT Study

In the study she presented, researchers reviewed the records of all patients with advanced (N2 or N3 disease) HNSCC who had been treated with chemoradiation from December 2003 to June 2007. Patients who had a complete response to treatment and underwent both PET-CT and a planned post-treatment neck dissection comprised the study group. A total of 32 patients were included, 28 males and four females, with a mean age of 56 years. All patients had stage IV disease at presentation. Mean follow-up after completion of chemoradiation was 20 months.

None of the patients had clinical signs of neck disease when PET-CT or neck dissections were performed. PET-CT showed positive results for residual nodal disease in 20 patients. These were compared to pathological findings from samples taken from neck dissection. Residual carcinoma was found in six of the 20 patients (30%) who had positive PET-CT findings, and in four of 12 patients (33%) who had negative PET-CT findings.