Complete cytoreduction for pseudomyxoma peritonei is optimal but maximal tumor debulking may be beneficial in patients in whom complete tumor removal cannot be achieved

Global gene expression in pseudomyxoma peritonei, with parallel development of two immortalized cell lines

Pseudomyxoma peritonei (PMP) is a rare tumor of appendiceal origin. Treatment is major cytoreductive surgery but morbidity is high. PMP is considered chemo-resistant; its molecular biology is understudied; and presently, there is no platform for pre-clinical drug testing. Here, we performed exon array analysis from laser micro-dissected PMP tissue and normal colonic epithelia. The array analysis identified 27 up-regulated and 34 down-regulated genes: candidate up-regulated genes included SLC16A4, DSC3, Aldolase B, EPHX4, and ARHGAP24; candidate down-regulated genes were MS4A12, TMIGD1 and Caspase-5. We confirmed differential expression of the candidate genes and their protein products using in-situ hybridization and immuno-histochemistry. In parallel, we established two primary PMP cell lines, N14A and N15A, and immortalized with an SV40 T-antigen lentiviral vector. We cross-checked for expression of the candidate genes (from the array analyses) using qPCR in the cell lines and demonstrated that the gene profiles were distinct from those of colorectal tumor libraries and commonly used colon cell lines. N14A and N15A were responsiveness to mitomycin and oxaliplatin. This study characterizes global gene expression in PMP, and the parallel development of the first immortalized PMP cell lines; fit for pre-clinical testing and PMP oncogene discovery.

Cytoreductive Surgery and Peritonectomy Procedures

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) has become widely accepted as an effective method of treating peritoneal metastases (PM) from various cancers. CRS performed with the goal of removing all the macroscopic disease and comprises of peritonectomy procedures and visceral resections. CRS is a technically challenging surgery that requires a considerable amount of skill and appropriate patient selection. This article is a review of the techniques and current recommendations for performing CRS.

Can a Benefit be Expected from Surgical Debulking of Unresectable Pseudomyxoma Peritonei?

PURPOSE

This study evaluated the role of surgical debulking in improving pseudomyxoma peritonei (PMP)-related symptoms if complete cytoreductive surgery (CCRS) of huge PMP is unachievable.

METHODS

This was a retrospective analysis of a prospective database of all patients in our tertiary care center treated for PMP between 1992 and 2014. All cases of surgical debulking in patients scheduled for CCRS that proved unachievable during the operation were selected for the present study.

RESULTS

Among the 338 patients operated on for PMP, 39 (11.5 %) had undergone surgical debulking because CCRS was unachievable. All of these patients were symptomatic before surgery, and the median PCI was 32 (5-39). More than 80 % of the disease burden was resected in 23 patients (59 %). Mortality and major morbidity rates were 2.5 and 23 %, respectively. After debulking surgery, symptoms gradually subsided over a median time of 23 months and 50 % of the patients no longer experienced PMP-related symptoms after a median follow-up of 24.5 months. After a median follow-up of 46.4 months (range 3-120), median overall (OS) and progression-free (PFS) survival times were 55.5 and 20 months, respectively. Five-year OS and PFS rates were 46 and 11 %, respectively.

CONCLUSIONS

Aggressive debulking surgery in case of unachievable CCRS for huge PMP can offer prolonged relief of PMP-related symptoms and long-term survival, in experienced centers that are able to be sufficiently aggressive to resect the major part of the disease, and conservative enough to achieve low mortality and good quality of life.

The results of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in 1200 patients with peritoneal malignancy

AIM

The study determined the outcome of 1200 consecutive patients treated for peritoneal malignancy in one surgical unit over a 20-year period.

METHOD

A retrospective analysis was conducted of a custom designed prospective database of patients undergoing surgery for peritoneal malignancy since 1994. Patient demographics, tumour type, extent of surgery and outcome were recorded.

RESULTS

Between 1994 and January 2014 (when the 1200th case had undergone surgery) 2956 patients were referred with a diagnosis of peritoneal malignancy. Pseudomyxoma peritonei of appendiceal origin was the pathology in 956/1200 (79.7%) patients. Other aetiologies included colorectal peritoneal metastases [89/1200 (7.4%)], abdominal mesothelioma [65/1200 (5.4%)] and miscellaneous [90/1200 (7.5%)]. Overall 863/1200 (71.9%) had complete cytoreduction, 294 (24.5%) had maximal tumour debulking and 43 (3.6%) had laparotomy only. The proportion undergoing complete cytoreduction per quartile of 300 patients was 60.7%, 65.0%, 77.0% and 80.3%. Laparotomy and biopsy fell from 6.4% in the first quartile to 2.7%, 1.7% and 1.3% in subsequent quartiles. The 30-day mortality in the four quartiles was 3.0%, 1.0%, 0.7% and 0.7%. The 5-year survival was 84% in the 636 patients with appendix tumours who had complete cytoreduction, 76% in the 38 with abdominal mesothelioma and 44% in the 60 with colorectal peritoneal metastases.

CONCLUSION

A centralized approach facilitated high volume experience in a single centre with an increase in the completeness of surgical excision rates and a reduction in mortality and morbidity over time.

Palliative Surgery for Pseudomyxoma Peritonei

Introduction:

Pseudomyxoma peritonei is a rare disease causing peritoneal carcinomatosis. In patients with extensive carcinomatosis, curative treatment is unachievable. Palliative debulking therapy is the only treatment in relieving symptoms. We report our results from palliative debulking surgery at a national pseudomyxoma peritonei center in Denmark.

Methods:

From January 2007 to October 2012, we performed 27 palliative operations for pseudomyxoma peritonei with debulking at our institution. All patients were evaluated and found eligible for palliative treatment only. Patients were prospectively registered, while perioperative data were collected retrospectively from patient records.

Results:

The majority of patients ( n = 25) received an omentectomy (93%) as the primary procedure. In total, 17 (63%) received additional surgery. Median operative time was 88 min (range: 33–160 min). Median stay at the recovery ward was 6 h (2–288 h). Median hospital stay was 8 days (4–105 days). In all, 23 (85%) patients had no in-hospital complications, whereas 4 patients experienced complications (15%). Two of the complications were mild (Clavien-Dindo grade II), and two experienced severe complications (grade III and IV). Thirty-day mortality was 0%. Median survival was 3.0 years (0.2–6.2 years).

Conclusion:

Palliative debulking is a safe procedure with an acceptable morbidity and mortality offering immediate disease control.

Hyperthermic Intraperitoneal Chemotherapy Following Cytoreductive Surgery Improves Outcome in Patients With Primary Appendiceal Mucinous Adenocarcinoma: A Pooled Analysis From Three Tertiary Care Centers

PURPOSE

Appendiceal mucinous neoplasms (AMN) are a rare heterogeneous group of diseases. In the absence of randomized trials, AMN management is controversial. The goal of this study was to evaluate the impact of hyperthermic intraperitoneal chemotherapy (HIPEC) after cytoreductive surgery on survival in AMN patients.

PATIENTS AND METHODS

Patient data including demographics, pathology, type of therapy, and outcomes were collected from Emory University, the Ohio State University, and Wayne State University databases. One of the three centers did not use HIPEC. Statistical analysis evaluating overall survival (OS) of AMN patients was performed.

RESULTS

Between 1990 and 2010, 163 AMN patients were identified. Histology showed 60 patients had diffuse peritoneal adenomucinosis, 88 had peritoneal mucinous carcinomatosis (PMCA), and 15 had PMCA with indeterminate or discordant features. Complete surgical resection was achieved in 76 patients. HIPEC was used in 79 patients. The median OS was 77 months for patients who received HIPEC compared with 25 months for patients who did not (p < .001). In multivariable analysis, histopathologic subtype (p < .001), complete surgical resection (p < .001), and HIPEC (p < .001) were independent predictors for improved OS. A survival advantage for AMN patients treated at HIPEC-treating centers was observed (p = .0026). After adjusting for HIPEC therapy, no significant survival difference was observed between the non-HIPEC-treating center and the HIPEC-treating centers (p = .094).

CONCLUSION

The addition of HIPEC to cytoreductive surgery likely provides a survival advantage and should be considered in the treatment strategy for AMN.

Secreted mucins in pseudomyxoma peritonei: pathophysiological significance and potential therapeutic prospects

Pseudomyxoma peritonei (PMP, ORPHA26790) is a clinical syndrome characterized by progressive dissemination of mucinous tumors and mucinous ascites in the abdomen and pelvis. PMP is a rare disease with an estimated incidence of 1-2 out of a million. Clinically, PMP usually presents with a variety of unspecific signs and symptoms, including abdominal pain and distention, ascites or even bowel obstruction. It is also diagnosed incidentally at surgical or non-surgical investigations of the abdominopelvic viscera. PMP is a neoplastic disease originating from a primary mucinous tumor of the appendix with a distinctive pattern of the peritoneal spread. Computed tomography and histopathology are the most reliable diagnostic modalities. The differential diagnosis of the disease includes secondary peritoneal carcinomatoses and some rare peritoneal conditions. Optimal elimination of mucin and the mucin-secreting tumor comprises the current standard of care for PMP offered in specialized centers as visceral resections and peritonectomy combined with intraperitoneal chemotherapy. This multidisciplinary approach has reportedly provided a median survival rate of 16.3 years, a median progression-free survival rate of 8.2 years and 10- and 15-year survival rates of 63% and 59%, respectively. Despite its indolent, bland nature as a neoplasm, PMP is a debilitating condition that severely impacts quality of life. It tends to be diagnosed at advanced stages and frequently recurs after treatment. Being ignored in research, however, PMP remains a challenging, enigmatic entity. Clinicopathological features of the PMP syndrome and its morbid complications closely correspond with the multifocal distribution of the secreted mucin collections and mucin-secreting implants. Novel strategies are thus required to facilitate macroscopic, as well as microscopic, elimination of mucin and its source as the key components of the disease. In this regard, MUC2, MUC5AC and MUC5B have been found as the secreted mucins of relevance in PMP. Development of mucin-targeted therapies could be a promising avenue for future research which is addressed in this article.

Current concepts in pseudomyxoma peritonei

Each year, about two per million individuals will be diagnosed with pseudomyxoma peritonei, a disease characterised by the intra-abdominal growth of neoplastic mucin-secreting cells on peritoneal surfaces. The distribution of the disease within the abdomen is not random but depends on physiological principles. Most cases derive from neoplasms of the appendix. In the past, the ovary was considered a common primary site. However, we now know that the ovary is only rarely the source of pseudomyxoma, and that lesions which would previously have been called "borderline mucinous tumours of the ovary" are typically metastatic from the appendix. The grade of the neoplastic cells in pseudomyxoma is an important prognostic factor, but unfortunately there is no consensus on terminology. An international expert group of pathologists and clinicians is currently working on the harmonisation of terminology in this field. Expertise in the management of pseudomyxoma can be achieved by concentrating the treatment of patients in specialised centres or through the development of networks.