That resulted in a calculation that, in this study, PET had a sensitivity of 75%; a specificity of 65%; a positive predictive value of 33%; and a negative predictive value of 92%, Dr. Brkovich said.
Explore This IssueApril 2006
While the role of the post-treatment neck dissection remains controversial, the surgeon must rely on a combination of clinical examination and imaging studies, Dr. Brkovich said. Our practice has been to perform a planned staged neck dissection on all N2/N3 necks as well as N1 necks with an incomplete response to treatment.
Based on this small prospective study it appears that PET imaging lacks adequate sensitivity and specificity to reliably predict the presence of residual metastatic disease after treatment.
However, Dr. Brkovich said that even though the numbers are small PET imaging may be a valuable guide to the surgeon. The negative PET scan may allow the surgeon to avoid a post-treatment neck dissection.
Based on this small prospective study it appears that PET imaging lacks adequate sensitivity and specificity to reliably predict the presence of residual metastatic disease after treatment. – -Victoria S. Brkovich, MD
Dr. Brkovich noted that her study is limited by the small numbers of patients, the lack of a pre-treatment baseline PET imaging studies, and the possibility that researchers used poor timing in scheduling post-treatment PET studies.
In a similar study, Christine Gourin, MD, Assistant Professor of Otolaryngology at the Medical College of Georgia in Augusta, considered whether the combination of PET and CT could be useful in identifying nodal disease following chemoradiation for advanced head and neck cancer.
The need for a less invasive procedure than neck dissection exists because the dissection is often planned following primary chemoradiation in patients with head and neck squamous cell cancer who demonstrate a complete response.
The need for dissection in these patients is controversial. In competing papers in 2004, one author suggested that everyone who survived chemoradiation needed the dissection to help plan post-treatment therapy. The second author suggested in his paper that only less than a complete response required a neck dissection.
We sought to investigate the utility of PET-CT in identifying patients with occult nodal disease following a complete response, Dr. Gourin said in her oral presentation at the Triological Society Meeting.
Dr. Gourin suggested that the PET-CT combination-which produces sharper images-could give doctors the information required to determine if the surgery was needed.
Insufficiency Specificity, Sensitivity
She reviewed the medical records of patients treated with primary chemoradiation for advanced head and neck squamous cell carcinoma with N2 or N3 disease from December 2003 through June 2005. Dr. Gourin found 17 patients who were irradiated with 7032 centiGray in once daily fractions over a seven week period during which nine patients received cisplatin and eight patients were treated with cisplatin and 5-flourouracil. The 17 patients achieved total responses and underwent planned neck dissection at 10 to 12 months. At 8 to 10 weeks post-treatment, the patients underwent a PET-CT imaging study.