[Application of intraoperative ultrasound in laparoscopic lymphadenectomy of gastric cancer].

OBJECTIVE

To explore the application value of intraoperative ultrasound (IU) in laparoscopic lymphadenectomy of gastric cancer.

METHODS

Patients with gastric cancer undergoing laparoscopic radical D2 gastrectomy at General Surgery of the Second Affiliated Hospital of Anhui Medical University between August 2016 and May 2018 were prospectively enrolled and were randomly divided into IU group (n=78) and conventional group (n=91). The conventional group underwent laparoscopy only. In IU group, the laparoscopy examination was followed with intraoperative ultrasound by ultrasound specialist. The lesser curvature, peripheral gastric organs and gastric lymph nodes were scanned. Lymph nodes were considered positive if maximum diameter was greater than 10 mm or internal hyperechoic features and normal oval shape were lost. The postoperative pathological results were used as the gold standard to analyze the sensitivity of positive lymph nodes by IU detection [true positive lymph nodes/(true positive lymph node+false negative lymph nodes)×100%], specificity [true negative lymph nodes/(true negative lymph nodes+false positive lymph nodes)×100%] and the accuracy rate[(true positive lymph nodes+ true negative lymph nodes/total lymph nodes)×100%]. A consistency check between N staging diagnosed by IU and by postoperative pathology was performed with Kappa test(Kappa>0.75 indicating good consistency). Number of dissected lymph node, number of positive lymph node detected by pathology and the operation time were compared between the IU group and the conventional group.

RESULTS

Among 169 gastric cancer patients, 95 were males and 74 were females with age of (63±8) years. Among 1 794 lymph nodes detected by IU from 78 patients in IU group, predicted positive lymph nodes were 832 and 740 positive nodes were confirmed by postoperative pathology. True positive lymph nodes were 679 and true negative lymph nodes were 901 by IU, and a total of 1 580 lymph nodes were accurately diagnosed by IU. The sensitivity and specificity of IU for N staging of gastric cancer were 91.8%(679/740) and 85.5%(901/1 054), respectively. Overall accuracy was 88.1%(1 580/1 794), which was in good accordance with postoperative N staging(Kappa=0.758). There was no significant difference in number of lymph node detected between the IU group and conventional group during laparoscopic gastric cancer surgery(23.0±6.9 vs. 22.0±7.7, t=0.880, P=0.380). However, the numbers of lymph nodes in the third station (No.10, No.11, No.12) in the IU group were significantly higher than those in the conventional group [No.10: median 1 (0-1) vs. 0 (0-1), Z=-6.307, P<0.001; No.11: median 1(0-2) vs. 0(0-1), Z=-5.895, P<0.001; No.12: median 1 (0-1) vs. 0 (0-1), Z=-6.693, P<0.001]. There was no significant difference in the number of positive lymph node between IU group and the conventional group(P>0.05), but the number of positive lymph nodes dissected in stage III patients of IU group was significantly higher than that in stage III patients of conventional group (14.6±4.8 vs. 14.0±3.6, t=2.531, P=0.011). The operative time of IU group was(272.0±12.0) minutes, which was significantly longer than (249.0±7.0) minutes of conventional group (t=14.638, P<0.001). However, with the increase of patients undergoing IU, the operation time of IU showed a downward trend. The average operation time of the last 20 patients was 264 minutes, and the average IU time was 15 minutes.

CONCLUSIONS

Intraoperative ultrasound is more accurate N-staging of gastric cancer. Although increasing operation time, it is helpful for lymph node dissection in laparoscopic gastric cancer surgery, especially by providing good support for laparoscopic No.10, No.11 and No.12 lymph nodes dissection.