• 3/5/2007
  • Barcelona, Spain
  • Bruce Sylvester
  • Doctor’s Guide (www.docguide.com)

Addition of fluorodeoxyglucose (FDG)-positron emission tomography (PET) to computed tomography (CT) alters gross tumour volume readings for a significant number of patients with head and neck cancer, which can affect treatment decisions.

The findings were presented in an oral session here on February 23rd at the International Meeting on Innovative Approaches in Head and Neck Oncology, sponsored by the European Head and Neck Society and the European Society for Therapeutic Radiology and Oncology (EHNS-ESTRO).

“Our findings suggest that, for tumours of the head and neck which are to be treated with primary chemoradiography, combined FDG-PET-CT will provide optimal treatment guidance compared to CT alone,” said presenter and lead investigator Christian Terhaard, MD, PhD, associate professor of radiology, University of Utrecht, Utrecht, The Netherlands.

The investigators compared the CT and FDG-PET-CT images of 109 patients treated at the University Medical Centre in Utrecht between 2003 and 2006 for primary squamous cell carcinoma of the head and neck (95%) or for recurrent disease (5%). The scans were taken using the same mould for each patient.

A radiation oncologist and a nuclear medicine physician matched and analysed the images and evaluated them for differences in the gross tumour volume and change of treatment preference.

Tumours were located in the pharynx (76%), larynx (11%) and oral cavity (13%). Advanced T-stage (tumour size and extent of primary tumour) of T3-4 appeared in 46% of the subjects; neck nodes were positive in 61%.

The researchers reported that the field of radiation was adapted, or altered, in 45% of subjects based on FDG-PET-CT compared with CT alone; this was due to a change on local extension of identified disease in 16% of subjects and a change of N-stage diagnosis in 22% of patients. In 6%, a second primary tumour site was located, leading to a change of treatment.

In 3% of patients, the disease was downstaged after FDG-PET-CT, and in 17% it was upstaged.

CT did not show the local extension of disease in 20% of subjects. In 7% of FDG-PET-CT images tumour extensions were not clear.

Generally, CT showed larger tumour volumes compared with FDG-PET-CT, the researchers reported. They also noted that diagnosis of a second primary tumour influenced the eventual choice of therapy.

“For head and neck tumours treated with primary [chemo] radiography combined FDG-PET-CT scanning should be the standard for [image guided radiotherapy],” the authors concluded.

Presentation title:
FDG-PET Combined With CT Considerably Alters Tumour Delineation for Radiotherapy for H&N Cancer Compared to CT Only. Abstract 24