PET imaging with F-18- fluorothymidine on patients with head and neck cancer prior to and during radiation therapy allows physicians to assess early loco-regional clinical outcomes, according to a study published in the October issue of The Journal of Nuclear Medicine.
Studies have shown F-18-fluorodeoxyglucose (FDG) PET may be used to assess treatment response, but may produce false positives. Researchers from Kagawa University in Japan studied 28 patients with head and neck squamous carcinomas (HNSCCs) between May 2006 and September 2010, who underwent both FDG and F-18- fluorothymidine (FLT) PET imaging before treatment, at four weeks after the start of treatment and again five weeks after therapy was finished. Both primary and metastatic lesions were assessed. The researchers were looking for regions of focally increased metabolism, which were analyzed in relation to residual accumulation and local disease control.
Researchers found that during radiation therapy, F-18-FLT uptake accumulation disappeared in 34 of 54 lesions (63 percent) and the negative predictive value was 97 percent. The negative predictive value for the F-18-FDG uptake was 100 percent, and only nine lesions (16 percent) in all showed complete absence of accumulation.
“The specificity and overall accuracy of F-FLT PET were significantly higher than those of F-FDG PET both during and after RT,” wrote the authors. The high significance, the authors said, was due to the results of the evaluations of the primary lesions.
“With the development of new molecular imaging agents, it’s now up to clinical researchers to utilize them to assess the characteristics of malignant tumors and their therapeutic response to chemotherapy, radiotherapy, and molecular targeting therapy,” Hiroshi Hoshikawa, MD, the study’s lead author, said in a press release. “We hope that our findings will be helpful in understanding the significance of F-18-FLT-PET.”