Correlation of endoscopic and histologic findings before and after treatment for nasopharyngeal carcinoma

Background. The endoscopic and histologic findings before and after radioth erapy (RT) for nasopharyngeal carcinoma (NPC) were correlated to study the sensitivity and specificity of endoscopic findings in predicting histologic results. The efficiacy of endoscopic examination and post-RT multiple site biopsies in detecting persistent disease was also evaluated. Methods. Seven hundred forty-six patients were evaluated. Pre-RT, biopsies were taken from both sides of the nasopharynx to assess the extent of tumor . Four to 16 weeks after RT, routine six-site biopsy specimens were taken f rom both roofs, lateral, and posterior walls of the nasopharynx and repeate d 2 weeks later. Endoscopic findings of exophytic growth, nodule, ulcer, an d submucosal bulge were considered "residual tumor," others were considered "no residual tumor." Persistent disease was defined as positive histologic findings 12 weeks after RT. Results. Before RT, sensitivity of endoscopic findings and biopsy specimens in detecting malignancy were 99.7% and 94.2%, respectively. After RT, sens itivity and specificity of endoscopic findings in predicting positive histo logic findings were 29% and 85.8%, respectively, with a positive predictive value of 34.9% and a negative predictive value of 82.2%. Of positive histo logic findings, 27.7% were missed in the first session of biopsies; 33.5% o f those with positive histologic findings turned out to have persistent dis ease. For prediction of persistent disease, the sensitivity and specificity of endoscopic findings were 40.4% and 84.4%, with a positive predictive va lue of 16.3% and a negative predictive value of 95%, and that of histologic findings in the first session of biopsies were 59.6% and 88.3%, respective ly, with a positive predictive value of 27.7% and a negative predictive val ue of 96.7%. Conclusions. Endoscopic findings alone have low sensitivity in predicting p ersistent disease, multiple sites biopsy specimens are indicated. Because o nly 1.9% of patients with endoscopic findings of "no residual tumor" and ne gative histologic findings in first session of biopsies had persistent dise ase. this group can be spared second biopsies. Repeat biopsies are indicate d for those with endoscopic findings of "residual tumor" or positive histol ogic findings in first session of biopsies to improve detection of persiste nt disease. (C) 2000 John Wiley & Sons, Inc.