Early FLT-PET/CT May Help Predict Head and Neck Cancer Outcomes

Dutch researchers undertook a prospective study to evaluate the association between findings from early sequential PET with the proliferation tracer 18F-FLT and clinical outcome among patients with squamous cell carcinoma of the head and neck who were undergoing radiotherapy, with or without concomitant chemotherapy.

Forty-eight patients participated in the study between July 2006 and August 2008. All were adults who had been newly diagnosed with stage II to stage IV cancer. Patients who had undergone surgery as primary tumor therapy were not eligible. Thirty patients received intensity-modulated radiation therapy and 18 underwent 3D conformal radiotherapy.

The patients underwent FLT-PET/CT scanning before starting radiotherapy. Forty-six underwent a second scan at two weeks after a median of seven radiotherapy fractions. A third scan, not originally part of the protocol, was given to 29 patients in the fourth week of treatment after a median of 18 fractions.

The findings showed that 18F-FLT uptake decreased significantly between consecutive scans. Patients who demonstrated an SUV_max decline of 45 percent or more and a gross tumor volume using visual delineation (GTV_VIS) that decreased by at least 31 percent during the first two weeks of treatment showed better three-year disease-free survival than the other patients: 88 percent versus 63 percent. In addition, a GTV_VIS decrease of more than the 31 percent in the fourth week of treatment week was also associated with better three-year locoregional control: 100 percent versus 68 percent.

The subset of patients who received concomitant chemotherapy showed the most pronounced association. Patients who were found to have at least a 31 percent decrease in GTV_VIS had a disease-free survival of 100 percent, while those who had less than a 31 percent decrease had a 50 percent disease-free survival.

The researchers concluded that early use of 18F-FLT PET, particularly during the second week of treatment, may be beneficial in personalizing patient management for head and neck cancer, steering treatment modifications during an early phase of therapy.