Objective: To ascertain whether fluorodeoxyglucose positron emission tomography is indicated for clinical staging of superficial cancer, we sought to determine if it accurately classifies tumor (T), regional nodal (N), and distant metastases (M), including distinguishing high-grade dysplasia (Tis) from invasive cancer (T1).
Methods: Fifty-eight superficial esophageal cancer patients had preoperative positron emission tomography, 53 (91%) fused with computed tomography. Tumor characteristics, esophagoscopy findings, and pTNM were compared with positron emission tomography cTNM. pT1 was subdivided into intramucosal cancers with lamina propria or muscularis mucosa invasion and submucosal cancers with inner or outer invasion.
Results: Fluorodeoxyglucose uptake increased with pT, from 5/11 (45%) for pTis to 11/16 (69%) for pT1 (outer submucosa), P=0.07, as it did for standardized uptake value, median 0 for pTis to 2.7 for pT1 (outer submucosa), P=0.06. Positron emission tomography could not differentiate Tis (5/11, 45%) from T1 (26/47, 55%; P=0.03). Regional nodal fluorodeoxyglucose uptake in three patients (standardized uptake value 2.8, 4.9, 11) was false positive; in six pN1 patients, it was false negative. Positron emission tomography had 0% sensitivity and positive predictive value for N1. There were no distant metastases; one patient developed a pulmonary metastasis 15 months postoperatively. Positron emission tomography detected three (5%) distant hypermetabolic sites, all synchronous tumors (papillary thyroid cancer, adrenal pheochromocytoma, rectal adenoma). Only increasing tumor length was related to greater fluorodeoxyglucose uptake (P=0.004) and higher standardized uptake value (P=0.001).
Conclusions: Because positron emission tomography can neither differentiate pTis from T1 nor classify T, N, and M, it is not indicated in staging superficial esophageal cancer. Finding a synchronous primary tumor in approximately every 20th patient is its only benefit. Better, less expensive screening tools are available for common synchronous malignancies.