Outcomes Post Beyond Total Mesorectal Excision Plane Resections Following Setting up Complex Colorectal Cancer Service in a District General Hospital.

Background: This study aims to validate the feasibility of a hub-and-spoke model for pelvic exenteration (PE) surgery while upholding favorable patient outcomes. Methods: A retrospective analysis of patients undergoing PE at our trust October 2017 and December 2023 was conducted. Descriptive statistics and Kaplan-Meier survival analysis were employed. Results: Sixty-seven patients underwent PE during the study period, mainly for locally advanced colorectal cancer (n=61, 91.04%). Minimally invasive surgery was performed in 16 cases (Robotic 3, 4.47% / Laparoscopic 13, 19.40) while the rest of patients 51 had open surgery (75.11%). Median hospital stay was 12 days (range:8-20). While 24 patients (35.82%) developed major complications (CD III-IV) post-surgery, there were no mortalities associated with pelvic exenteration in this study. Of the 67 patients undergoing surgery with curative intent, negative margins (R0 resection) were achieved in 57 patients (85.12%). This is comparable to outcomes reported by the PelvEx collaborative (85.07% versus 79.8%). At a median follow-up of 22 months, 15 patient (22.38%) recurred with 10.44% local recurrence rate. The 2 years overall and disease-free survival were 85.31% and 77.0.36%, respectively. Conclusion: Our study suggests that a nascent PE service, supported by specialist expertise and resources, can achieve good surgical outcomes within a district general hospital.

In vitro study of radiosensitivity in colorectal cancer cell lines associated with Lynch syndrome.

Introduction: Lynch syndrome patients have an inherited predisposition to cancer due to a deficiency in DNA mismatch repair (MMR) genes which could lead to a higher risk of developing cancer if exposed to ionizing radiation. This pilot study aims to reveal the association between MMR deficiency and radiosensitivity at both a CT relevant low dose (20 mGy) and a therapeutic higher dose (2 Gy). Methods: Human colorectal cancer cell lines with (dMMR) or without MMR deficiency (pMMR) were analyzed before and after exposure to radiation using cellular and cytogenetic analyses i.e., clonogenic assay to determine cell reproductive death; sister chromatid exchange (SCE) assay to detect the exchange of DNA between sister chromatids; γH2AX assay to analyze DNA damage repair; and apoptosis analysis to compare cell death response. The advantages and limitations of these assays were assessed in vitro, and their applicability and feasibility investigated for their potential to be used for further studies using clinical samples. Results: Results from the clonogenic assay indicated that the pMMR cell line (HT29) was significantly more radio-resistant than the dMMR cell lines (HCT116, SW48, and LoVo) after 2 Gy X-irradiation. Both cell type and radiation dose had a significant effect on the yield of SCEs/chromosome. When the yield of SCEs/chromosome for the irradiated samples (2 Gy) was normalized against the controls, no significant difference was observed between the cell lines. For the γH2AX assay, 0, 20 mGy and 2 Gy were examined at post-exposure time points of 30 min (min), 4 and 24 h (h). Statistical analysis revealed that HT29 was only significantly more radio-resistant than the MLH1-deficient cells lines, but not the MSH2-deficient cell line. Apoptosis analysis (4 Gy) revealed that HT29 was significantly more radio-resistant than HCT116 albeit with very few apoptotic cells observed. Discussion: Overall, this study showed radio-resistance of the MMR proficient cell line in some assays, but not in the others. All methods used within this study have been validated; however, due to the limitations associated with cancer cell lines, the next step will be to use these assays in clinical samples in an effort to understand the biological and mechanistic effects of radiation in Lynch patients as well as the health implications.