TORONTO--The use of whole-body fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) offers an opportunity to improve the outcome for patients with advanced head and neck cancers. Two papers presented at the 45th annual meeting of the Society of Nuclear Medicine found that FDG-PET was more accurate than conventional imaging for the diagnosis of regional and distant recurrence.
"The prognosis for head and neck cancer is poor, with survival rates only at 20% at 5 years," said Val J. Lowe, MD, director of PET, St. Louis University Health Sciences Center. The majority of relapses, he said, occur within the first year after completion of therapy. "We postulated that earlier detection of recurrence may improve survival in this group and that PET may allow earlier diagnosis of recurrent disease," he said.
The St. Louis study included 44 patients with advanced head and neck cancer (stage III and IV) who were participating in a neoadjuvant organ preservation protocol that included chemotherapy, surgical salvage, and postoperative radiation therapy. PET scans were performed twice during the first post-treatment year, at 4 months and 10 months. Additional scans have been taken each subsequent year that the patients are alive and enrolled in the study.
After therapy, patients were divided into subsets of complete response (27 patients) or residual disease (6 patients). Eleven patients were withdrawn from the study due to an inability to tolerate imaging or to development of an immediate recurrence in the first year.
The group of complete responders to therapy was further divided into two subsets: patient without evidence of disease (13) or with recurrence (14) at least 1 year after completion of therapy.
In the recurrent subset, 5 patients had recurrence detected by PET alone; 3 by PET and other correlative imaging (CI) such as head and neck CT and chest x-ray; 4 by PET and physical exam with negative CI; and 2 by PET, CI, and physical exam. Only PET detected all recurrences in these patients, and in the first group where PET was the only identifier, 4 of the 5 patients were diagnosed at the first 4-month scan.
"PET can detect head and neck tumor recurrence when it may be undetectable by other clinical methods," Dr. Lowe said. "Our research suggests that FDG-PET scans should be performed at least twice in the first year post-treatment."
California Study
A study by the Northern California PET Imaging Center and several California medical centers included 51 patients with known or suspected recurrence of head and neck cancer. Each patient received a whole-body FDG-PET scan, and presence or absence of tumor was established in 49 patients using surgery (26), biopsy (8), and imaging/clinical follow-up (15).
In a subset of 33 cases, FDG-PET was compared with CT and MRI. In these patients, PET sensitivity for local recurrence was 90% vs 74% for CT/MRI. For regional recurrence, PET sensitivity was 89% vs 84% for CT/MRI. In addition, in 12 of the 51 patients, PET correctly identified 15 sites of distant metastases (eight lung, two mediastinal/hilar, two liver, two bone, and one retro-orbital).
"Pretreatment imaging with FDG-PET avoids the morbidity and cost of attempted curative surgery or radiotherapy in patients with undiagnosed distant recurrences who may really be candidates for chemotherapy," said Dr. Elma Abella-Columna, research fellow at the Northern California PET Imaging Center.
