Survival outcomes used to validate version 9 of the American Joint Committee on Cancer staging system for appendiceal cancer

Defining a 'cells to society' research framework for appendiceal tumours

Tumours of the appendix - a vestigial digestive organ attached to the colon - are rare. Although we estimate that around 3,000 new appendiceal cancer cases are diagnosed annually in the USA, the challenges of accurately diagnosing and identifying this tumour type suggest that this number may underestimate true population incidence. In the current absence of disease-specific screening and diagnostic imaging modalities, or well-established risk factors, the incidental discovery of appendix tumours is often prompted by acute presentations mimicking appendicitis or when the tumour has already spread into the abdominal cavity - wherein the potential misclassification of appendiceal tumours as malignancies of the colon and ovaries also increases. Notwithstanding these diagnostic difficulties, our understanding of appendix carcinogenesis has advanced in recent years. However, there persist considerable challenges to accelerating the pace of research discoveries towards the path to improved treatments and cures for patients with this group of orphan malignancies. The premise of this Expert Recommendation article is to discuss the current state of the field, to delineate unique challenges for the study of appendiceal tumours, and to propose key priority research areas that will deliver a more complete picture of appendix carcinogenesis and metastasis. The Appendix Cancer Pseudomyxoma Peritonei (ACPMP) Research Foundation Scientific Think Tank delivered a consensus of core research priorities for appendiceal tumours that are poised to be ground-breaking and transformative for scientific discovery and innovation. On the basis of these six research areas, here, we define the first 'cells to society' research framework for appendix tumours.

Analysis of survival and prognostic factors in appendix adenocarcinoma and mucinous carcinoma

This study aimed to compare mucinous carcinoma and adenocarcinoma of the appendix in terms of survival and investigate the risk factors influencing survival. The data for this study were retrieved from the SEER database (SEER Research Plus 17 registries). Patients diagnosed with appendix cancer between 2004 and 2019 were included. Demographic data, such as age, gender, marital status, and year of diagnosis, along with oncological variables like stage, surgery, chemotherapy, radiotherapy, and survival time, were extracted from the SEER database. Pathological subtypes were classified as adenocarcinoma (AC) and mucinous adenocarcinoma (MAC) based on the College of American Pathologists guidelines. Patients with other pathological subtypes or missing data were excluded from the study. This study included 4524 patients, with 2118 (46.8%) classified as AC and 2406 (53.2%) as MAC. There was no significant difference in mean age between AC and MAC groups (63.22 ± 14.30 vs. 59.46 ± 14.07, p = 0.483). AC was more common in males, while MAC was more prevalent in females (46.8% vs. 53.2%; 55.6% vs. 44.4%, p < 0.001, respectively). Married status was high in both groups (p = 0.001). While no difference was found in white race distribution, the black race was more prevalent in the AC group (57.1% vs. 42.9%, p < 0.001). Grade 1 tumors were more frequent in the AC group, whereas Grades 2 and 3 were more common in the MAC group (p < 0.001). Stages 1, 2, and 3 were more prevalent in the AC group, while the majority of MAC cases were at Stage 4. Surgery rates were higher in the AC group (98.6% vs. 96.4%, p < 0.001). Chemotherapy was used more frequently in the MAC group (50.9% vs. 40.6%, p < 0.001), while radiotherapy rates were similar in both groups (p = 0.498). The mean follow-up period was 55.70 ± 47.2 months. Five- and ten-year survival rates for the MAC group were 64.4% and 50.2%, respectively, higher than the AC group's rates of 54.2% and 39.7% (p < 0.001). The overall risk of mortality was 1.4 times higher in the AC group compared to the MAC group (p < 0.001, HR: 1.377 [CI 95% 1.259-1.507]). While adenocarcinomas and mucinous adenocarcinomas have similar incidences, non-metastatic adenocarcinomas were more frequently observed. In contrast, mucinous adenocarcinomas often exhibited distant metastases. Nevertheless, the survival rate was higher in mucinous adenocarcinomas.

Appendiceal adenocarcinoma: Current concepts & challenges

Appendiceal adenocarcinoma (ApAC) is a rare malignancy, comprising less than 1 % of all gastrointestinal tumors. The current World Health Organization classifies ApAC as mucinous or nonmucinous. Mucinous ApAC are composed of pools of mucin lined by cells with low- and high-grade cytology and areas of infiltrative invasion. Nonmucinous ApAC histologically resemble conventional colorectal adenocarcinomas and have a worse prognosis than their mucinous counterpart. Unfortunately, the nomenclature and histologic classification of ApAC, specifically the mucinous subtype, has changed several times throughout the years, contributing to diagnostic confusion for pathologists. The treatment for mucinous ApAC differs from that of other appendiceal mucinous neoplasms, thus accurate diagnosis is key to patient management and outcome. This review discusses the current classification and staging of ApAC with a particular emphasis on the mucinous subtype and peritoneal disease, as these areas are the most challenging for practicing surgical pathologists.

Mucinous neoplasm of the appendix: A case report and review of literature

BACKGROUND

Appendiceal mucinous neoplasms (AMNs), although not classified as rare, are relatively uncommon tumors most often discovered incidentally during colorectal surgery. Accurate identification of AMNs is difficult due to non-specific symptoms, overlapping tumor markers with other conditions, and the potential for misdiagnosis. This underscores the urgent need for precision in diagnosis to prevent severe complications.

CASE SUMMARY

This case report describes the unexpected discovery and treatment of a low-grade AMN (LAMN) in a 74-year-old man undergoing laparoscopic hemicolectomy for transverse colon adenocarcinoma (AC). Preoperatively, non-specific gastrointestinal symptoms and elevated tumor markers masked the presence of AMN. The tumor, presumed to be an AMN peritoneal cyst intraoperatively, was confirmed as LAMN through histopathological examination. The neoplasm exhibited mucin accumulation and a distinct immunohistochemical profile: Positive for Homeobox protein CDX-2, Cytokeratin 20, special AT-rich sequence-binding protein 2, and Mucin 2 but negative for cytokeratin 7 and Paired box gene 8. This profile aids in distinguishing appendiceal and ovarian mucinous tumors. Postoperative recovery was uncomplicated, and the patient initiated adjuvant chemotherapy for the colon AC.

CONCLUSION

This case highlights the diagnostic complexity of AMNs, emphasizing the need for vigilant identification to avert potential complications, such as pseudomyxoma peritonei.

Current Status of Treatment among Patients with Appendiceal Tumors-Old Challenges and New Solutions?

The 5th edition of the World Health Organization (WHO) classification of tumors of the digestive system distinguishes four categories of appendiceal tumors (ATs): serrated lesions and polyps, mucinous neoplasms, adenocarcinomas, and neuroendocrine neoplasms (NENs). The differential diagnosis of ATs can be challenging in medical practice, due to their rarity and lack of data from randomized controlled trials on a large, diverse group of patients. ATs are usually noted in specimens obtained during appendectomies due to clinical acute appendicitis. In the European population, most ATs (65%) occur over the age of 50 and among women (56.8%). According to histological type, 54.6% are neuroendocrine tumors (NETs); 26.8% cystic, mucinous, and serous neoplasms; and 18.6% adenocarcinoma not otherwise specified (NOS). On pathologic analysis, most AT findings are benign lesions or small NENs that do not require further therapeutic measures. The presence of appendiceal mucinous neoplasm (AMN) can lead to pseudomyxoma peritonei (PMP). While the multimodal treatment for abdominal malignancies has evolved over the past several decades, the clinical workup and treatment of ATs remain a challenge. Therefore, this review aims to describe the diagnostic possibilities, molecular-based diagnosis, staging, differences in the treatment process, and prognostic factors associated with ATs.