[Establishment and preliminary application of tissue response grading system following neoadjuvant chemotherapy]

To establish the tissue response grading (TRG) system following neoadjuvant chemotherapy and to investigate its application in the gastric cancer patients who received neoadjuvant chemotherapy.

Data of 30 cT3-4N0-3M0 gastric cancer cases who received neoadjuvant chemotherapy and operation from May 2017 to February 2018 at Department of Gastrointestinal Surgery, West China Hospital were analyzed retrospectively. The edema degree of gastrointestinal tract and perigastric tissues, intraoperative effusion, and fibrosis of tumor and lymph nodes bearing tissues which could be divided into 4 categories constituted the core parameters of the TRG system following neoadjuvant chemotherapy. Four categories of edema: grade 0, no obvious tissue edema; grade 1, slight tissue edema and swelling, no obvious effusion when dissecting the capsule of connective tissues; grade 2, moderate tissue edema and swelling, a few effusion when dissecting the capsule of connective tissues; grade 3, severe tissue edema and swelling with high tension on the capsule of connective tissues, tension blister could be observed in some patients, continuous effusion when dissecting the capsule of connective tissues. Four categories of intraoperative effusion: grade 0, no obvious effusion; grade 1, slight effusion and a few intraperitoneal exudation; grade 2, moderate effusion and continuous intraperitoneal exudation necessitating interrupted suction; grade 3, severe effusion and continuous intraperitoneal exudation necessitating constant suction. Four categories of fibrosis: grade 0, no fibrosis; grade 1, slight fibrosis with threadiness fibrous bands, clear dissecting space could be found between the fibrous tissues and adventitia/normal tissues; grade 2, moderate fibrosis with flaky fibrous tissues, the difficulty of tissue and lymph nodes dissection increased although dissecting space could be found between the fibrous tissues and adventitia/normal tissues; grade 3, severe fibrosis with hard and flaky fibrous membrane, the difficulty of tissue and lymph nodes dissection increased extremely and the fibrous tissues merges with adventitia/normal tissues without dissecting space. The relationships of TRG system with tumor response evaluation by computed tomography (CT), tumor regression score, surgical duration, number of retrieved lymph nodes, number of metastatic lymph nodes, number of enlarged lymph nodes seen in the preoperative CT scans as well as postoperative complications were analyzed using t test, χ² test and logistic regression model.

Nineteen male and 11 female patients with a mean age of(59.1±9.4) years were enrolled. There were 17 cases of grade 1, 12 cases of grade 2 and 1 case of grade 3 for tissue edema, while the corresponding number was 14, 15 and 1 for intraoperative effusion and 15, 14 and 1 for fibrosis respectively. There were no significant differences among the different degrees of tissue edema, intraoperative effusion and fibrosis in terms of the tumor response evaluation by CT and tumor regression score (all P>0.05). The results of logistics regression showed that tumor response evaluation by CT was related with the degree of tissue edema (P=0.012) and intraoperative effusion (P=0.007), rather than the degree of fibrosis (P=0.527). However, tumor regression score was not related with the degree of tissue edema(P=0.345), intraoperative effusion (P=0.159) and fibrosis (P=0.207). Surgical duration of one case with all grade 3 in tissue edema, intraoperative effusion and fibrosis was 408 minutes, which was longer than those with grade 1 and grade 2 patients [(295.9±40.1) minutes and (293.1±34.3) minutes, respectively]; the number of retrieved lymph nodes, metastatic lymph nodes, and enlarged lymph nodes seen in the preoperative CT scans of this case with all grade 3 were 25, 4 and 1, which were all less than those with grade 1 and grade 2 (42.3±11.9 and 38.5±18.2, 7.3±9.1 and 8.1±9.7, 1.8±1.6 and 2.3±1.3, respectively). There were no significant differences between grade 1 and grade 2 of tissue edema, intraoperative effusion and fibrosis in terms of surgical duration, retrieved lymph nodes, metastatic lymph nodes and enlarged lymph nodes seen in the preoperative CT scans(all P>0.05). Four patients suffered from pulmonary complications and 2 patients experienced slight lymphatic, and all leakage were cured by conservative therapies. There were no significant differences among the different grades of tissue edema, intraoperative effusion and fibrosis in terms of the operation-associated complications (all P>0.05).

The tissue response grading system can assist the judgment of operation difficulty and reflect the effectiveness of neoadjuvant chemotherapy to some extent, which has the possibility of applications.