Improved detection of recurrent laryngeal tumor after radiotherapy using (18)FDG-PET as initial method

Timely detection of recurrent laryngeal tumor after radiation is an important predictive factor for curation as well as preservation of laryngeal function. Direct laryngoscopy under general anesthesia with taking of biopsies is the standard diagnostic procedure to detect recurrence when suspicion is raised. This, however, is an invasive and potentially damaging technique. Hence, a non-invasive diagnostic procedure, such as (18)FDG-PET to stratify patients for direct laryngoscopy could be useful. (18)FDG-PET is interpreted visually so that observer variation may affect clinical practice. In the present study, we therefore investigated this aspect of reproducibility.

Thirty consecutive patients suspected of recurrent laryngeal carcinoma after radiotherapy underwent (18)FDG-PET and direct laryngoscopy under general anesthesia with taking of biopsies. (18)FDG-PET scans were reported by nine nuclear medicine physicians and residents, using a three-point scaling system. The reference was the absence or appearance of a local recurrence in the 12 months following (18)FDG-PET.

Eight patients had biopsy proven recurrent laryngeal carcinoma. Sensitivity of (18)FDG-PET was 88% (95% CI 53-98%) and specificity was 82% (95% CI 62-93%). The observers had a moderate to reasonable agreement (weighted kappa 0.45 (95% CI 0.20-0.69)) vs. the clinical gold standard and interobserver kappa was 0.54 (95% CI 0.40-0.69).

(18)FDG-PET seems to be a promising technique to detect recurrent laryngeal carcinoma after radiotherapy, and selecting patients for direct laryngoscopy. This will avoid futile invasive procedures. Interobserver agreement and variability is reasonable using this technique, but training is necessary. Studies comparing different strategies to select patients for direct laryngoscopy in case of suspected recurrence are warranted.