Pembrolizumab for Microsatellite Instability-High or Mismatch Repair Deficient Small Bowel Adenocarcinoma or Appendiceal Adenocarcinoma

Some adult patients with microsatellite instability-high (MSI-H)/mismatch repair deficient (dMMR) small bowel adenocarcinoma might benefit from pembrolizumab in controlling the disease (i.e., some patients achieved a partial or complete response after treatment). These findings are based on 2 single-arm studies (i.e., no comparator) with fewer than 20 patients in each study, which limits the certainty of the findings. The longer-term benefit of pembrolizumab is unclear, as some outcomes (e.g., progression-free survival, overall survival) were not reached at the time of data analysis. The safety of pembrolizumab in patients with MSI-H/dMMR small bowel adenocarcinoma is unknown (no evidence was found for this population). No evidence was identified regarding the clinical effectiveness of pembrolizumab monotherapy for patients with MSI-H/dMMR appendiceal adenocarcinoma. No evidence was identified regarding the cost-effectiveness of pembrolizumab monotherapy for patients with MSI-H/dMMR small bowel adenocarcinoma or appendiceal adenocarcinoma. No evidence-based guidelines were identified regarding pembrolizumab monotherapy for patients with MSI-H/dMMR appendiceal adenocarcinoma. One guideline was identified that recommends pembrolizumab as an option for initial or subsequent therapy in patients with advanced or metastatic MSI-H/dMMR small bowel adenocarcinoma.

Lymphocyte-to-monocyte ratio predicts survival after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

Aim: Lymphocyte-to-monocyte ratio (LMR) predicts overall survival (OS) in patients with colorectal cancer. We explored LMR in patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). Materials & methods: We identified all patients undergoing CRS/HIPEC for colorectal or appendiceal adenocarcinoma at our institution. We analyzed LMR’s relationship with clinicopathologic variables with Kaplan–Meier log-rank survival analyses and multivariable Cox regression models with 5-year OS. Results: Two hundred and sixteen patients underwent CRS/HIPEC. Five-year OS for low LMR (≤3.71) was 35.2 versus 60.4% for elevated LMR (hazard ratio [HR]: 2.0; 95% CI: 1.1–3.5; p = 0.02). On multivariable Cox-regression, elevated LMR was significantly associated with OS (p ≤ 0.05). Conclusion: LMR is an independent predictor of OS in patients undergoing CRS/HIPEC for colorectal and appendiceal adenocarcinoma.

Utility of chemotherapy given before and/or after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for appendiceal adenocarcinoma with peritoneal metastases.

e16276 Background: Appendiceal adenocarcinoma is relatively rare and often diagnosed incidentally during operations for acute appendicitis. It is commonly associated, either at time of initial presentation or upon recurrence, with peritoneal metastases. A typical treatment strategy for patients with peritoneal disease includes cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). Extrapolating largely from literature in colorectal cancer, chemotherapy is frequently given before and/or after CRS/HIPEC though high-level evidence to support this is lacking. We sought to evaluate the effect of systemic chemotherapy on survival. Methods: Utilizing a database of CRS/HIPEC procedures at University of Colorado Hospital from 2008 to present we retrospectively reviewed cases of appendiceal adenocarcinoma. Data collected included staging, histologic grade, chemotherapy given, surgical outcomes, and time to disease recurrence. Patients without adequate information regarding treatment, or without at least 1 year of clinical follow-up, were excluded. Associations between administration of chemotherapy or histologic grade and 1-year DFS were analyzed using Fisher’s exact test, and logistic regression was used to assess whether 1-year DFS were different in chemotherapy-treated patients when adjusted for histologic grade. Results: In total, 117 cases reviewed indicated an appendiceal pathology. Of these, 54 cases in a total of 51 patients met the specified criteria for pathology and completeness and length of follow-up information. The average age was 58 years (range 26-81 years). Adenocarcinoma was graded as low in 15 (28%) cases, intermediate in 18 (33%) cases, and high in 21 (39%) cases. 23 (43%) patients received no chemotherapy while 31 (57%) received chemotherapy before and/or after surgery. In the overall population, there was no significant effect of chemotherapy on survival, with 1-year DFS demonstrated in 74.2% of patients receiving some chemotherapy and 70% in patients not receiving chemotherapy (p = 0.765). One-year DFS was achieved in 86% of low-grade cases, 61% of intermediate-grade cases, and 71% of high-grade cases, though this was also not statistically significant (p = 0.254). Furthermore, when 1-year DFS between chemotherapy and non-chemotherapy patients was adjusted for grade, there was again no significant interaction (odds ratio = 0.48, 95% C.I. (0.13-1.64), p = 0.763). Conclusions: In this small, single-institution experience of patients with peritoneal appendiceal adenocarcinoma, there was no significant effect of chemotherapy administration on 1-year DFS. These findings are likely affected by significant confounding with the small sample size and retrospective nature of the data. Further investigation on a larger scale is warranted.

Appendiceal adenocarcinoma with breast metastases

Malignant lesions of the vermiform appendix make up a rare subset of colorectal cancer. While colorectal cancer frequently metastasises to the liver, lung, regional lymph nodes and peritoneum, metastasis to the breast is extremely rare. Here, we describe the case of an 84-year-old woman who had the incidental finding of appendiceal adenocarcinoma following emergency laparoscopic appendectomy. She declined further operative or adjuvant treatment for her disease. She represented 1 year later with metastatic appendiceal adenocarcinoma disease to her left breast. A simple mastectomy for symptomatic treatment was performed. In this report, we describe the first case of appendiceal adenocarcinoma metastases to the breast. Due to its rarity, there is a paucity of evidence related to the management of this condition. The limited evidence is reviewed and discussed.

836 Presentation, Clinical Outcomes and Prognosis of Primary Appendiceal Adenocarcinoma; Single Centre Experience

Background Appendiceal adenocarcinoma is a rare condition. The aim of the study is to determine the pattern of clinical picture, histological diagnosis and prognosis of the disease on patients in our area. Method A retrospective data analysis of patients who underwent appendicectomies from January 2011 to December 2019 in Northumbria NHS Trust. Records of patients with histologically diagnosed appendiceal adenocarcinoma were studied for their demographics, clinical features, laboratory, radiological results, operative notes and histological types. Results 13 out of 3138 appendicectomies (0.41%: 6 Males, 7 Females with mean age of 69.84 years) were found to have primary appendiceal adenocarcinoma. Almost all the patients presented with clinical picture in keeping of acute appendicitis. 9 patients underwent emergency appendicectomies. 4 patients were treated conservatively. Appendiceal adenocarcinoma was diagnosed based on colonoscopy in 1 patient, CT scan in 1, post-appendicectomy histology in 9 patients, 2 post RHC histologies. Survival rate was 71.4% after 1 year, 64.3% after 2 years and 42.9% after 3 years. Overall median survival time for all TNM stages was 39.0 (95% CI, 15.72 to 62.27) months. Mean survival time was best in stage II 56.33 (95% CI, 48.86 to 63.80) months. Conclusions Preoperative diagnosis is very difficult. Overall prognosis is poor.