Circular RNA is a novel endogenous non‐coding RNA that can serve as a biomarker because of its stable loop structure. We investigated and examined the utility of plasma circERBB2 as a prognostic biomarker in 70 patients with gastric cancer who underwent gastrectomy. We investigated by real‐time quantitative PCR the circERBB2 concentrations in the preoperative and postoperative plasma and the circERBB2 expression in the resected tumors. The relationships between circERBB2 concentration in plasma and the clinicopathological features and prognosis were analyzed. circERBB2 was detected in the preoperative plasma samples of 37 patients. The presence of circERBB2 in preoperative plasma (high group) was significantly correlated with lymph node metastasis (P = .035) and tended to be correlated with men (P = .069). Both relapse‐free and overall survival were significantly poor in the high group (P = .001 and P = .009, respectively). The Cox proportional‐hazard model revealed that the high group was an independent prognostic factor of relapse‐free survival (P = .038). Among 16 patients of the high group, 13 patients did not show circERBB2 in the postoperative plasma. The concentration of circERBB2 in plasma was significantly higher in patients with recurrent cancer than those recurrence‐free patients (P < .001). In 2 patients with recurrent cancer, plasma circERBB2 concentrations were increased, whereas, in 2 recurrence‐free patients, these concentrations hardly changed during the treatment progress. The circERBB2 concentrations in preoperative plasma samples can be considered as a noninvasive prognostic biomarker for gastric cancer. Furthermore, monitoring the postoperative plasma circERBB2 concentrations may be useful for detecting gastric cancer recurrences.

Esophageal squamous cell carcinoma (ESCC) is a lethal malignancy. However, there are few useful markers for diagnosis and treatment. Glutathione S‐transferase Pi 1 (GSTP1) has been reported as a predictor of malignancy or anticancer drug resistance in some cancers. We investigated the association of GSTP1 expression with the malignancy or drug resistance in ESCC cell lines and clinical tissue samples. Proliferation and apoptosis assays regarding GSTP1 expression were examined in ESCC cell lines. Proliferation of GSTP1 knockdown cells was significantly decreased (P < .01), and the frequency of early apoptosis was increased (P < .05). Invasion capacity of GSTP1 knockdown cells was slightly decreased in transwell assay. These results suggest that GSTP1 plays an important role in malignant potential. To examine the effects of GSTP1 on drug resistance, chemosensitivity assay and apoptosis assay under cisplatin exposure were carried out. Viability of GSTP1 knockdown cells treated with cisplatin was lower than that of control cells (P < .01). Moreover, the frequency of early and late apoptosis in GSTP1 knockdown cells was markedly increased over that of control cells by cisplatin exposure (P < .01). In immunohistochemistry assay of resected tissue samples, GSTP1 expression was significantly associated with clinical downstaging (P = .04) in 72 ESCC patients with neoadjuvant chemotherapy. Furthermore, there was a significant association between GSTP1 expression in resected tissue and biopsy samples in 34 ESCC patients without neoadjuvant chemotherapy (P = .02). In summary, GSTP1 was related to malignant potential and may be a predictive marker of drug resistance in ESCC patients.

Background/Aim: This study aimed to investigate the efficacy of additional surgical resection (ASR) after endoscopic submucosal dissection (ESD) for superficial esophageal cancer (SEC). Patients and Methods: Clinicopathological features and prognoses were analyzed in esophageal cancer (EC) cases with the indication for additional treatments (AT) after ESD (37 cases) and in cases that underwent primary resection (13 cases). Results: Sixteen out of 37 cases underwent ASR. The remaining 21 cases underwent other treatments or observation. Although all ASR cases are alive without recurrence, recurrence developed in 2 non-ASR cases. Residual tumors were detected in 2 ASR cases. All 4 cases were T1b and positive for lymph vessel invasion (ly+). No significant difference was observed in surgical outcomes between ASR and primary surgical resection (PSR) cases. Conclusion: AT need to be considered for T1b and ly+ cases, and ASR is one of the effective AT. The safety of ASR was similar to PSR for SEC.