Overall Survival is More Closely Associated with Peritoneal than Primary Appendiceal Pathological Grade in Pseudomyxoma Peritonei with Discordant Pathology

Reclassification of Appendiceal Mucinous Neoplasms and Associated Pseudomyxoma Peritonei According to the Peritoneal Surface Oncology Group International Consensus: Clinicopathological Reflections of a Two-Center Cohort Study

BACKGROUND

International consensus on classifications of appendiceal mucinous neoplasms (AMNs) and associated pseudomyxoma peritonei (PMP) have been carefully made but clinicopathological associations supporting decision making remain scarce.

OBJECTIVE

This study aimed to assess interdependence between AMNs and PMP and provide directions for clinical management.

METHODS

This two-center retrospective cohort study reviewed patients with PMP treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy between 2005 and 2021. The primary objective was to reassess histopathologic grade of AMNs and PMP according to the Peritoneal Surface Oncology Group International classification and to establish its interdependence. Secondary outcomes were recurrence rate, PMP grade progression, ovarian involvement, and overall survival (OS).

RESULTS

Of 105 patients included, 78 (74.3%) had low-grade AMNs as the primary tumor, 8 (7.6%) had high-grade AMNs, 7 (6.7%) had mucinous adenocarcinoma (MAC), 1 (0.9%) had MAC with signet ring cells (SRC), and 11 (10.5%) had unidentified tumors. Overall, 11 patients (10.5%) had no PMP, 21 (20.0%) had acellular mucin, 56 (53.3%) had low-grade PMP, 12 (11.4%) had high-grade PMP, and 5 (4.8%) had PMP-SRC. In 11 cases (13.3%), AMNs and matching PMP grade differed. Over a 16-year follow-up, recurrence occurred in 31.8%, with three cases showing histopathologically changed PMP. Ovarian involvement was observed in 43/65 females (66.2%). Median OS was 13.8 years, and 5-year OS rates were 100%, 74.4%, 44.4%, and 20% for acellular mucin, low-grade PMP, high-grade PMP and PMP-SRC, respectively (p < 0.001).

CONCLUSIONS

AMN histology does not always reflects its associated PMP grade, while PMP grade strongly influences survival. Ovarian involvement and recurrent PMP showing unchanged histopathological features are common.

Analysis of therapeutic effect of cell reduction combined with intraperitoneal thermoperfusion chemotherapy in treatment of peritoneal pseudomyxoma

BACKGROUND

Pseudomyxoma peritonei is a rare tumor that can produce a biological behavior similar to that of a malignant tumor. Surgical resection combined with chemotherapy is the traditional treatment method, but the effect is not good. Cell reduction (CRS) combined with intraperitoneal thermoperfusion chemotherapy (HIPEC) has become a new method for the treatment of peritoneal pseudomyxoma (PMP).

AIM

To find out if CRS and HIPEC can be used safely and effectively to treat PMP.

METHODS

This is an observational study. Clinical data of PMP patients treated with CRS + HIPEC at our hospital from January 2013 to June 2023 was collated and analyzed. The main outcome measures were overall survival (OS), and the secondary outcome measures were the incidence of surgical complications and serious adverse events. Complications were graded according to common adverse event evaluation criteria. Peritoneal tumor staging was performed using the peritoneal tumor index (PCI) scoring system, and a cell reduction degree (CCR) score was performed after CRS. CCR-0 and CCR-1 were considered satisfactory CRS.

RESULTS

A total of 186 patients with PMP were included, with a median age of 56 (48-64) years, 65 (34.9%) years in males, and 121 (65.1%) years in females. The median PCI score was 28 (20-34) points. The median operative time was 300 (211-430) minutes, and no significant complications occurred. 91.4% (170/186) were from the appendix, 53.2% (99/186) were from the low grade, and 30.6% (57/186) were from the high grade. CCR scores showed that 55 patients (29.6%) achieved satisfactory CRS, and 113 patients (60.8%) did not achieve satisfactory CRS. The fatality rate at 30 days after surgery was 2.7% (5/186), 1.6% (3/186) needed a second operation, and the fatality rate at 90 days was 4.3% (8/186). The total incidence of III-IV complications was 43.0% (80/186), among which the higher incidence was mainly anemia (27.4%, 51/186), electrolyte disturbance (11.6%, 21/181), and albumin decrease (7.5%, 14/186). The main complications associated with abdominal surgery were gastrointestinal anastomotic leakage (2.2%, 4/186), abdominal hemorrhage (2.2%, 4/186), and abdominal infection (4.3%, 8/186). The median follow-up was 38.1 (95%CI: 31.2-45.1) months. The 5-year OS of PMP patients treated with CRS + HIPEC was 50.3% (95%CI: 40.7%-59.9%), and the median survival time was 66.1 (95%CI: 43.1-89.1) months. The results of the survival analysis showed that patients with a low pathological grade, a low PCI, and a satisfactory CCR score had a higher survival rate (all P < 0.05). 5-year OS was 88.9% (95%CI: 68.3%-100.0%) in CCR-0 patients, 77.6% (95%CI: 62.7%-92.5%) in CCR-1 patients, and 42.0% (95%CI: 29.5%-54.5%) in CCR-2/3 patients.

CONCLUSION

The application of CRS + HIPEC in PMP is safe and feasible, and the survival benefit is high, especially in those who achieve satisfactory CRS, which can significantly extend the OS.

Current clinical practices of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC)

Treatment of peritoneal surface malignancies makes physicians face demanding and new-fangled problems, as there are many uncertain aspects considering the outcomes of affected patients' prognoses. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are associated with favorable long-term outcomes in carefully selected patients with peritoneal metastases (PM). We aim to summarize the current results about the initial malignancies and their peritoneal spreads. The current literature has been scrutinized, and studies between 2016 and 2022 were included wherein long-term, progression-free (PFS), and overall survival (OS) data were considered relevant information. Medline, Embase, and Google Scholar have been the main sources. Hereby, we cover all the primer malignancies: gastric, ovarian, and colorectal cancers with peritoneal metastases (PM), malignant peritoneal mesothelioma, and pseudomyxoma peritonei. Examining the advances in the current peer-reviewed literature about the indications of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), target groups, risk factors, and other influencing elements, we intend to provide a complex state-of-the-art report, establishing the relevant aspects of that emerging treatment method.

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.

Defining a role for systemic chemotherapy in local and advanced appendix adenocarcinoma

BACKGROUND

Appendix adenocarcinomas (AAs) are rare tumours that often present late, with a propensity for peritoneal metastases (PMs). This study aimed to evaluate outcomes of AA patients undergoing cytoreductive surgery (CRS) with curative intent and determine the role of systemic chemotherapy.

MATERIALS AND METHODS

Data were collected from a prospective database and classified according to World Health Organization (WHO) 2019 classification. Tumour clearance from CRS was described using a completeness of cytoreduction (CC) score ranging from 0 [no residual disease (RD)] to 3 (>2.5 cm RD). Patients with CC0-2 CRS received hyperthermic intraperitoneal chemotherapy (HIPEC). Systemic chemotherapy was categorised as 'prior' (>6 months before), 'neoadjuvant' (<6 months before), 'adjuvant' (<6 months after CC0-1 CRS) or 'palliative' (after CC2-3 CRS). Analyses used Kaplan-Meier and Cox regression methods.

RESULTS

Between January 2005 and August 2021, 216 AA patients were identified for inclusion. Median age was 59 years (21-81 years). CRS/HIPEC was carried out in 182 (84%) patients, of whom 164/182 (76%) had mitomycin C HIPEC. CC0-1 was achieved in 172 (80%) patients. Systemic chemotherapy was given to 97 (45%) patients from the whole cohort and to 37/46 (80%) patients with positive nodes. Median overall survival (OS) was 122 months (95% confidence interval 61-182 months). After multivariate analysis, patients with acellular and lower-grade PM had similar OS to those with localised (M0) disease (P = 0.59 and P = 0.19). For patients with positive nodes, systemic chemotherapy was associated with reduced risk of death compared to no chemotherapy (P < 0.0019).

CONCLUSION

This study identifies AA patients with positive lymph nodes derive the most benefit from systemic chemotherapy. We confirm the prognostic importance of stage and peritoneal grade, with excellent outcomes in patients with acellular mucin and lower-grade PM.

Pseudomyxoma Peritonei Arising from Urachal Mucinous Neoplasms: a Case Series and Updated Literature Review

To report a case series of patients with pseudomyxoma peritonei (PMP) from urachal mucinous neoplasm (UMN) treated with CRS and HIPEC at a high-volume referral centre, along with an updated literature review. Retrospective review of cases treated between 2000 and 2021. A literature review using MEDLINE and Google Scholar databases was performed. Clinical presentation of PMP from UMN is heterogeneous, and common symptoms are abdominal distension, weight loss, fatigue and haematuria. At least one tumour marker among CEA, CA 19.9, and CA 125 was elevated in the six cases reported, and 5/6 had a preoperative working diagnosis of urachal mucinous neoplasm suspected on detailed cross-sectional imaging. Complete cytoreduction was achieved in five cases, while one patient underwent maximal tumour debulking. Histological findings mirrored the findings of PMP from appendiceal mucinous neoplasms (AMN). Overall survival ranged between 43 and 141 months after complete cytoreduction. On literature review, 76 cases have been reported to date. Complete cytoreduction is associated with good prognosis for patients with PMP from UMN. A definitive classification system is still not available.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13193-022-01694-5.

Conditional Survival Following Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy for Peritoneal Surface Malignancies: An Analysis from the US HIPEC Collaborative

INTRODUCTION

The long-term prognosis of patients who undergo cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal surface malignancies (PSM) varies considerably on the basis of histological and operative factors. While overall survival (OS) estimates are used to inform adjuvant therapy and surveillance strategies, conditional survival may provide more clinically relevant estimates of prognosis by accounting for disease-free time elapsed.

PATIENTS AND METHODS

All patients from 12 academic institutions who underwent CRS ± HIPEC for PSM from 2000 to 2017 were retrospectively analyzed. OS and disease-free survival (DFS) rates were calculated using the Kaplan-Meier method while conditional overall (COS) and conditional disease-free survival (CDFS) rates were calculated at 1, 2, or 3 years from surgery for different tumor histologies.

RESULTS

Overall, 1610 patients underwent CRS ± HIPEC. Among patients with benign appendiceal mucinous tumors (N = 460), 5-year OS and COS at 3 years were 92.1% and 96.3% (Δ4.2%), respectively. For patients with well-differentiated appendiceal cancers (N = 400), 5-year OS and COS at 3 years were 76.3% and 88.3% (Δ12.0%), respectively. For patients with high-grade appendiceal cancers (N = 258), 5-year OS and COS at 3 years were 43.8% and 75.4% (Δ31.6%), respectively. For patients with colorectal cancers (N = 362), 5-year OS and COS at 3 years were 31.8% and 67.3% (Δ35.5%), respectively. For patients with peritoneal mesothelioma (N = 130), 5-year OS and COS at 3 years were 67.6% and 89.7% (Δ22.1%), respectively. Similar trends were observed for DFS/CDFS.

CONCLUSION

The conditional survival of patients undergoing CRS ± HIPEC for PSM is associated with tumor histology. COS and CDFS provide a more accurate, dynamic estimate of survival than OS and DFS, especially for patients with more aggressive histologies.

[Current treatment recommendations for pseudomyxoma peritonei]

BACKGROUND

The term pseudomyxoma peritonei (PMP) describes a clinical syndrome characterized by the presence of gelatinous intraperitoneal accumulation of mucus. It mostly originates from a mucocele of the vermiform appendix. Affected patients are often asymptomatic for a long time. Because of its indolent nature it is usually diagnosed at an advanced stage. Clinical presentation is determined by the dissemination of the tumor.

METHOD

A search and analysis of the current literature were carried out.

RESULTS

Based on the morphological characteristics PMP subtypes with various malignant potential can be differentiated. The prognosis depends on the histopathological differentiation and the clinical stage. The treatment spectrum varies from laparoscopic appendectomy to complete cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC).

CONCLUSION

Due to the rarity of PMP there are no prospective randomized studies. Therefore, there is still controversy regarding the best stage-dependent treatment strategy. This review article attempts to clarify the optimal management of mucinous neoplasms of the appendix and PMP taking the clinical presentation and the histological differentiation into consideration.