The introduction of immunotherapy has changed the traditional paradigms in cancer treatment and has demonstrated substantial clinical benefits across various malignancies. However, this progress is accompanied with emerging challenges, such as immune evasion and low response rates to immunotherapy. As an immunomodulatory molecule, zymogen granule protein 16 (ZG16) plays a crucial role in immunotherapy by inhibiting the binding of programmed death 1 (PD-1) to its ligand PD-L1, preventing immune evasion and restoring the immune system's ability to recognize and eliminate tumor cells. ZG16 is downregulated in multiple gastrointestinal tumors, and its regulatory mechanisms vary depending on the tumor type. ZG16 expression is closely associated with patient prognosis, and it has been identified as a favorable prognostic marker in colorectal cancer. This article provides a systematic overview of the structural characteristics, expression regulation mechanisms, and antitumor immune functions of ZG16.

Objective:To evaluate the short-term efficacy of modified laparoscopic extralevator abdominoperineal excision (L-ELAPE) for ultralow rectal cancer.Methods:The retrospective cohort study was conducted.The clinicopathological data of 60 patients with ultralow rectal cancer who underwent L-ELAPE in the Tangdu Hospital Affiliated to the Air Force Medical University from January 2014 to July 2018 were collected. There were 32 males and 28 females, aged (58±12)years, with a range from 38 to 75 years. Of the 60 patients, 30 patients undergoing modified L-ELAPE were allocated into modified group and 30 patients undergoing traditional L-ELAPE were allocated into control group. For patients in the modified group, the abdominal procedure is the same as the traditional L-ELAPE. The improvements were as follows: (1) when tumor was located in the anterior rectal wall, the patient was plased into the jackknife position before starting the perineal procedure. (2) In order to prevent the small intestine from falling into the presacral space after surgery, the pelvic floor peritoneum was closed under laparoscopy and the biological patch was placed if necessary. For patients in the control group, the whole procedure was performed in the lithotomy position and the biological patch was sutured at the levator ani muscle. Observation indicators: (1) surgical situations; (2) postoperative situations; (3) follow-up. Follow-up was conducted by outpatient examinations and pelvic computed tomography (CT) examination at 3 months after surgery to assess the small intestine falling into the presacral space up to January 2019. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was analyzed using the t test. Count data were described as absolute numbers, and comparison between groups was analyzed using the chi-square test or Fisher′s exact probability. Results:(1) Surgical situations: patients in the two groups completed surgeries successfully, without tranversion to laparostomy or death within 1 month after operation. The operation time, volume of intraoperative blood loss, the number of lymph node harvested, quality score of the whole group specimens, quality score of anterior wall tumor specimens were (359±105)minutes, (192±99)mL, 17±6, 4.1±0.8, 4.7±0.5 for the modified group, respectively, versus (268±37)minutes, (136±61)mL, 15±5, 3.5±0.7, 3.9±0.7 for the control group, respectively. There were significant differences in the operation time, the quality score of the whole group specimens and the quality score of anterior wall tumor specimens between the two groups ( t=2.613, 2.130, 2.871, P<0.05). There was no significant difference in the volume of intraoperative blood loss or the number of lymph node harvested between the two groups ( t=1.521, 0.864, P>0.05). (2) Postoperative situations: the time to first liquid food intake, time to urinary catheter removal, the level of C-reactive protein at the first postoperative day, duration of postoperative hospital stay and cases with perineal complications were (3.3±1.1)days, (8.7±4.8)days, (85±27)mg/L, (8.5±4.5)days and 4 for the modified group, respectively, versus (2.7±1.4)days, (7.7±2.8)days, (79±25)mg/L, (7.7±2.2)days and 5 for the control group. There was no significant difference in the time to first liquid food intake, time to urinary catheter removal, the level of C-reactive protein at the first postoperative day, duration of postoperative hospital stay between the two groups ( t=1.311, 1.520, 0.521, 0.509, P>0.05). There was no significant difference in the perineal complications between the two groups ( P>0.05). All patients with perineal complications were cured after drainage, wound management, nutritional support and extention of hospital stay. (3) Follow-up: all patients were followed up after surgery. The modified group and the control group had 2 cases and 19 cases of small intestine falling into the presacral space showed by the pelvic CT examination at the postoperative 3 months, respectively, showing a significant difference between the two groups ( χ2=21.172, P<0.05). Conclusions:Modified L-ELAPE is safe and feasible for the ultralow rectal cancer, which can provide a better exposure and specimen quality for the tumor located at anterior rectal wall and reduce the incidence of small intestine falling into the presacral space. However, it has longer operation time.