Andreas Thalheimer

Background: The local and systemic activation and regulation of the immune system by malignant cells during carcinogenesis is highly complex with involvement of the innate and acquired immune system. Despite the fact that malignant cells do have antigenic properties their immunogenic effects are minor suggesting tumor induced mechanisms to circumvent cancer immunosurveillance. The aim of this study is the analysis of tumor immune escape mechanisms in a colorectal liver metastases mouse model at different points in time during tumor growth. Methods: CT26.WT murine colon carcinoma cells were injected intraportally in Balb/c mice after median laparotomy using a standardized injection technique. Metastatic tumor growth in the liver was examined by standard histological procedures at defined points in time during metastatic growth. Liver tissue with metastases was additionally analyzed for cytokines, T cell markers and Fas/Fas-L expression using immunohistochemistry, immunofluorescence and RT-PCR. Comparisons were performed by analysis of variance or paired and unpaired t test when appropriate. Results: Intraportal injection of colon carcinoma cells resulted in a gradual and time dependent metastatic growth. T cells of regulatory phenotype (CD4+CD25+Foxp3+) which might play a role in protumoral immune response were found to infiltrate peritumoral tissue increasingly during carcinogenesis. Expression of cytokines IL-10, TGF-β and TNF-α were increased during tumor growth whereas IFN-γ showed a decrease of the expression from day 10 on following an initial increase. Moreover, liver metastases of murine colon carcinoma show an up-regulation of FAS-L on tumor cell surface with a decreased expression of FAS from day 10 on. CD8+ T cells express FAS and show an increased rate of apoptosis at perimetastatic location. Conclusions: This study describes cellular and macromolecular changes contributing to immunological escape mechanisms during metastatic growth in a colorectal liver metastases mouse model simulating the situation in human cancer.

To evaluate clinical outcome after preoperative short-course radiotherapy for rectal cancer with twice daily fractions of 2.9 Gy to a total dose of 29 Gy and adjuvant chemotherapy for pathological stage UICC ≥ II. 118 patients (median age 64 years; male : female ratio 2.5 : 1) with pathological proven rectal cancer (clinical stage II 50%, III 41.5%, IV 8.5%) were treated preoperatively with twice daily radiotherapy of 2.9 Gy single fraction dose to a total dose of 29 Gy; surgery was performed immediately in the following week with total mesorectal excision (TME). Adjuvant 5-FU based chemotherapy was planned for pathological stage UICC ≥ II. After low anterior resection (70%) and abdominoperineal resection (30%), pathology showed stage UICC I (27.1%), II (25.4%), III (37.3%) and IV (9.3%). Perioperative mortality was 3.4% and perioperative complications were observed in 22.8% of the patients. Adjuvant chemotherapy was given in 75.3% of patients with pathological stage UICC ≥ II. After median follow-up of 46 months, five-year overall survival was 67%, cancer-specific survival 76%, local control 92% and freedom from systemic progression 75%. Late toxicity > grade II was observed in 11% of the patients. Preoperative short-course radiotherapy, total mesorectal excision and adjuvant chemotherapy for pathological stage UICC ≥ II achieved excellent local control and favorable survival.

Background: The development of therapeutic strategies for treatment of metastasized colorectal carcinoma requires biologically relevant and adequate animal models generating both metastases and the dissemination of tumor cells. Methods: To prove the efficiency of orthotopic implantation concerning induction of minimal residual disease (MRD) colorectal cancer tissue from 10 patients was transplanted orthotopically into nude mice. In the intraportal injection model 1 × 10⁶ HT-29 human colon cancer cells were injected. We investigated by histological studies and CK-20 RT-PCR the occurrence of hematogenous metastases and the dissemination of human colon cancer cells in bone marrow. Results: Following orthotopic implantation of human colon cancer tissue the lymph node and hepatic metastasis rates were low. MRD as reflected by CK-20 positivity of the bone marrow was present in 22.2%. The intraportal injection of 1 × 10⁶ HT-29 human colon cancer cells produced hepatic metastases in up to 89% of all animals. The intraportal injection of 1 × 10⁶ cells also generated MRD in the bone marrow in 63% of animals. Conclusions: The intraportal injection model represents a biologically relevant and adequate animal model for the induction of both reproducible hepatic metastasis and MRD in the bone marrow. In this regard it seems to be superior to the orthotopic implantation model.

Background: The success rate of laparoscopic adjustable gastric banding (LAGB)in the treatment of morbid obesity isvery variable. A reasonable preoperative selection of eligible patients seems to be important for a successful outcome of LAGB. In the present study, criteria were investigated to predict the outcome of LAGB. Methods: 85 morbidly obese patients were operated with LAGB between 1999 and 2005. 71of these patients were analysed according to several possible predictive parameters of success or failure of LAGB. Success was defined as excess bodyweight loss (EBWL) > 50% without band removal, failure was defined as EBWL < 20% and/or band removal. Median follow-up was 27 months (range 8–90 months). Results: After LAGB a median EBWL of 43%(–41 to171.5%) was observed in all patients with a decrease in BMI of 8.0 kg/m² (– 9 to 35 kg/m²). The success rate after LAGB was 37%, the failure rate 19.7%. Female sex (p = 0.023), baseline weight (p = 0.024), and eating behaviour after LAGB (p = 0.008) were significant predictors of success following LAGB, whereas complications such as port dislocation and reoperation after LAGB did not have a significant impact on a successful course following LAGB. Significant predictors of failure were male sex (p = 0.038) and missing physical activity after LAGB (p = 0.045), where as the eating behaviour did not have a significant effect concerning failure following LAGB. Baseline excess body weight (EBW) was identified as an independent predictor of failure in a multivariate analysis. Conclusion: According to the results of this study, female patients with a lower EBW who improve their postoperative eating behaviour have the best chanceof success following LAGB.

The development of new therapeutic strategies for treatment of metastasized colorectal carcinoma requires biologically relevant and adequate animal models that generate both reproducible metastasis and the dissemination of tumor cells in the form of so-called minimal residual disease (MRD), an expression of the systemic character of neoplastic disease.

Gastrointestinal stromal tumors (GISTs) are most often associated with oncogenic mutations of the KIT gene resulting in activation of the tyrosine kinase receptor KIT. Familial GIST syndrome based on a hereditary predisposition to develop GIST owing to a germline mutation is exceedingly rare. We describe a kindred with familial GIST displaying a novel germline mutation in exon 17. Three siblings (2 females, 1 male; 42 to 49 y) underwent surgery for multiple intra-abdominal tumors within a 3-year period. Their father had been operated on for gastric and jejunal tumors 20 years previously. The GIST was confirmed by immunohistochemistry in each sibling. Tumor and blood samples of the family members were analyzed for mutations in KIT and platelet-derived growth factor receptor (PDGFRalpha) genes. All examined lesions were of spindle cell type with expression of CD117. The tumor material exhibited a novel point mutation in codon 822 in exon 17 resulting in the replacement of asparagine by tyrosine (N822Y). The same mutation was detected in the father's blood sample. One healthy brother of the 3 siblings showed a wild-type sequence of the KIT gene. The germline mutation in exon 17 of the KIT gene identified in this kindred is very different from previously reported mutations of the KIT gene in familial GIST. Although the penetrance of KIT mutations is as yet unknown, assessment of the unaffected kindred of GIST patients for the presence of this mutation could help to distinguish individuals at high risk from those at virtually no risk.

This study was designed to quantify the temporary loop ileostomy-related morbidity in patients with colorectal cancer and contrast the morbidity rates after ileostomy closure before, during, and after the start of adjuvant therapy. Between 1997 and 2004, 120 patients with colorectal carcinoma underwent colorectal resection and creation of a temporary loop ileostomy to protect the low anastomosis. Stoma-related complications and perioperative morbidity after ileostomy closure were assessed retrospectively by reviewing the medical records. Sixteen of the 120 patients (13.3 percent) suffered stoma-related complications, requiring early ileostomy closure in three. After ileostomy closure, anastomotic leakage of the ileoileostomy occurred in 3 of the 120 patients (2.5 percent), 2 of them died postoperatively (1.7 percent). The rate of minor complications (16.7 percent in all patients) was much higher in patients undergoing adjuvant chemotherapy or radiochemotherapy (25.5 percent) than in patients receiving no additional therapy (9.2 percent). In the former patients, there was a trend toward fewer complications when ileostomy closure was performed before (12.5 percent), rather than during (42.9 percent) or after (21.2 percent), the start of adjuvant therapy. The morbidity following closure of a temporary loop ileostomy in colorectal cancer patients is much higher in patients receiving adjuvant chemotherapy or radiochemotherapy. The morbidity, however, might possibly be lowered to the level of patients receiving no additional therapy if ileostomy closure is performed before the start of adjuvant therapy.