Metastasized colorectal cancer (CRC) is associated with a poor prognosis and rapid disease progression. Besides hepatic metastasis, peritoneal carcinomatosis is the major cause of death in Union for International Cancer Control (UICC) stage IV CRC patients. Insights into differential site-specific reconstitution of tumor cells and the corresponding tumor microenvironment are still missing. Here, we analyzed the transcriptome of single cells derived from murine multivisceral CRC and delineated the intermetastatic cellular heterogeneity regarding tumor epithelium, stroma, and immune cells. Interestingly, we found an intercellular site-specific network of cancer-associated fibroblasts and tumor epithelium during peritoneal metastasis as well as an autologous feed-forward loop in cancer stem cells. We furthermore deciphered a metastatic dysfunctional adaptive immunity by a loss of B cell–dependent antigen presentation and consecutive effector T cell exhaustion. Furthermore, we demonstrated major similarities of this murine metastatic CRC model with human disease and — based on the results of our analysis — provided an auspicious site-specific immunomodulatory treatment approach for stage IV CRC by intraperitoneal checkpoint inhibition.

To investigate the influence of remote ischemic preconditioning (RIPC) on anastomotic integrity. Sixty male Wistar rats were randomized to six groups. The control group (n = 10) had an end-to-end ileal anastomosis without RIPC. The preconditioned groups (n = 34) varied in time of ischemia and time of reperfusion. One group received the amino acid L-arginine before constructing the anastomosis (n = 9). On postoperative day 4, the rats were re-laparotomized, and bursting pressure, hydroxyproline concentration, intra-abdominal adhesions, and a histological score concerning the mucosal ischemic injury were collected. The data are given as median (range). On postoperative day 4, median bursting pressure was 124 mmHg (60-146 mmHg) in the control group. The experimental groups did not show a statistically significant difference (P > 0.05). Regarding the hydroxyproline concentration, we did not find any significant variation in the experimental groups. We detected significantly less mucosal injury in the RIPC groups. Furthermore, we assessed more extensive intra-abdominal adhesions in the preconditioned groups than in the control group. RIPC directly before performing small bowel anastomosis does not affect anastomotic stability in the early period, as seen in ischemic preconditioning.

Clinical data indicate that laparoscopic surgery reduces postoperative inflammatory response and benefits patient recovery. Little is known about the mechanisms involved in reduced systemic and local inflammation and the contribution of reduced trauma to the abdominal wall and the parietal peritoneum. Included were 61 patients, who underwent elective colorectal resection without intraabdominal complications; 17 received a completely laparoscopic, 13 a laparoscopically- assisted procedure and 31 open surgery. Local inflammatory response was quantified by measurement of intraperitoneal leukocytes and IL-6 levels during the first 4 days after surgery. There was no statistical difference between the groups in systemic inflammatory parameters and intraperitoneal leukocytes. Intraperitoneal interleukin-6 was significantly lower in the laparoscopic group than in the laparoscopically-assisted and open group on postoperative day 1 (26.16 versus 43.25 versus 40.83 ng/ml; p = 0.001). No difference between the groups was recorded on POD 2–4. Intraperitoneal interleukin-6 showed a correlation with duration of hospital stay on POD 1 (0.233, p = 0.036), but not on POD 2–4. Patients who developed a surgical wound infection showed higher levels of intraperitoneal interleukin-6 on postoperative day 2–4 (POD 2: 42.56 versus 30.02 ng/ml, p = 0.03), POD 3: 36.52 versus 23.62 ng/ml, p = 0.06 and POD 4: 34.43 versus 19.99 ng/ml, p = 0.046). Extraabdominal infections had no impact. The analysis shows an attenuated intraperitoneal inflammatory response on POD 1 in completely laparoscopically-operated patients, associated with a quicker recovery. This effect cannot be observed in patients, who underwent a laparoscopically-assisted or open procedure. Factors inflicting additional trauma to the abdominal wall and parietal peritoneum promote the intraperitoneal inflammation process.

Obesity is a global epidemic characterized by energy disequilibrium, metabolic disorders, and fat mass development that greatly affect the health status of individuals. There is evidence that the intake of a high-fat diet and overweight are associated with the incidence of colorectal cancer (CRC). Metabolic surgery has been associated with improvements in obesity-related comorbidities and a reduction in the overall cancer risk. However, the underlying mechanism by which metabolic surgery reduces the risk of CRC remains unknown. To understand the antitumoral mechanism of bariatric surgery, we analyzed the development of CRC after Roux-en-Y gastric bypass (RYGB) surgery in an RYGB-CRC mouse model. Here, we showed that RYGB surgery substantially reduced primary tumorigenesis and prevented metastasis. This protective effect was mediated by bile acid (BA) exclusion from the proximal small intestine, leading to BA diversion in the preceding parts of the gastrointestinal tract and in circulation. The diverted BA profile in RYGB mice showed antitumoral and antimetastatic effects that were verified by BA exclusion of the proximal small bowel without the systemic metabolic installations of RYGB surgery by a cholecystointestinal shunt (CIS) surgery. RYGB surgery thus leads to reduced primary BAs and elevated secondary BAs in circulation. In a translational study involving patients with CRC with metachronous liver metastases, we confirmed that reduced primary BA concentrations in the serum were associated with prolonged time to metastasis, underscoring the critical role of BAs in CRC progression and metastatic development.

The indication for hepatic resection (HR) in patients suffering from liver metastases (LM) other than colorectal and neuroendocrine tumors is one focus of current multidisciplinary, oncologic considerations. This study retrospectively analyzes outcome after HR for non-colorectal, non-neuroendocrine (NCNNE) LM in the absence of distant or extrahepatic metastases. We included 100 consecutive patients undergoing HR for isolated NCNNE LM from a prospective database in our institution, including postoperative follow-up. Primary tumors were of mesodermal origin in 44%, of ectodermal origin in 29% and of entodermal origin in 27%. Survival analysis was performed by univariate and multivariable methods. Mean follow-up after hepatic surgery was 3.6 years (0.25–16). Median age at the time of HR was 59.5 years. Kaplan-Meier-estimated survival after liver resection was 56.8%, 34.3% and 24.5% after 5, 10 and 15 years, respectively. Univariate analysis after HR revealed residual disease (hepatic or primary; p = 0.02), female gender (p = 0.013), entodermal origin (p = 0.009) and early onset of metastatic disease (≤24 months, p = 0.002), as negative prognostic factors. Multivariable survival analysis confirmed residual disease, female gender, entodermal embryologic origin and early onset of metastatic disease (≤24 months) as independent negative prognostic factors. Overall outcome after HR of NCNNE LM results in acceptable long-term outcome. Although individual decision-making today mostly relies on clinical experience for this type of disease, risk factors derived from the embryologic origin of the tumor might help in patient selection.