F-18 FDG PET/CT as a post-operative follow-up tool for evaluation of the patients with gastric adenocarcinoma.

Abstract

Objectives: To investigate the value of FDG PET/CT in post-operative follow-up evaluation of patients (pts) with gastric adenocarcinoma.

Methods: Sixty-one pts (43 men and 18 women; 58 ± 11 years) performed post-operative FDG PET/CT scans either for routine surveillance (RS, n=53) or for clinical suspicion (CS, n=8, abnormal CT image findings in 7, increased tumor marker level in 3). Initial pathologic stages included: I in 26 (24 RS/2 CS), II in 13 (13 RS/0 CS), III in 10 (8 RS/2 CS), and IV in 12 (8 RS/4 CS). The mean follow-up period after operation was 29.3 ± 16.6 (5-61) months (mo). The diagnosis was based on histopathologic findings or clinical follow-up for more than 1 year..

Results: Nine pts were proven to reveal malignant lesions including 7 distant metastases and 2 secondary malignancies, with overall sensitivity (SN) 88.9% (8/9), specificity (SP) 92.3% (48/52), PPV 66.7% (8/12), NPV 98.0% (48/49), and accuracy (ACC) 91.8% (56/61), respectively. Among 53 pts for RS, 2 pts had metastases (initial stage/duration between operation and recurrence: T3N3M0/10 mo; T3N3M0/18 mo) and 2 pts had secondary malignancies in colon (T2bN0M0/49 mo; T1N0M0/60 mo), with SN 75.0% (3/4), SP 91.8% (45/49), PPV 42.9% (3/7), NPV 97.8% (45/46), and ACC 92.3% (48/53). Of 8 patients with CS, 5 had metastases [IIIB (n = 1) and IV (n = 4, all N3)/15.1 ± 5.5 (10-25) mo], with SN 100% (5/5), SP 100% (3/3), PPV 100%(5/5), NPV 100% (3/3), and ACC 100% (8/8).

Conclusions: Although the included number is small, this data demonstrates that FDG PET/CT is a useful post-operative follow-up tool for evaluation of recurrence or secondary malignancy in pts with gastric adenocarcinoma, not only in clinically suspicious cases but also in routine follow-up.