Peritoneal Cancer

Updated: Dec 10, 2016
  • Author: Wissam Bleibel, MD; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
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Overview

Practice Essentials

Peritoneal neoplasia can originate de novo from the peritoneal tissues (primary) or invade or metastasize into the peritoneum from adjacent or remote organs (secondary). Primary peritoneal cancers, some of which have been implicated in many cases of carcinomas of unknown primary origin, include ovarian cancer arising in women several years after bilateral oophorectomy. Other described primary peritoneal cancers and tumors include malignant mesothelioma, benign papillary mesothelioma, desmoplastic small round cell tumors, peritoneal angiosarcoma, leiomyomatosis peritonealis disseminata (LPD), and peritoneal hemangiomatosis.

Signs and symptoms

Primary peritoneal carcinoma usually manifests with abdominal distention and diffuse nonspecific abdominal pain secondary to ascites. This tumor is described almost exclusively in women.

Patients with malignant peritoneal mesothelioma usually manifest with symptoms and signs of advanced disease, including the following:

  • Abdominal pain
  • Ascites
  • Weight loss
  • An abdominal mass

See Clinical Presentation for more detail.

Diagnosis

The workup of peritoneal lesions includes peritoneal lavage cytology, as follows:

  • Peritoneal lavage can be performed using a percutaneous closed technique or at the time of laparoscopy or laparotomy
  • The sensitivity of the test results depends on the ability to completely lavage all regions of the peritoneal cavity and the ability to detect cancer cells being shed into the peritoneal cavity by the tumor

Laparoscopy or laparotomy

  • Direct visualization of the peritoneal surfaces along with palpation of the abdominal contents is by far the most sensitive modality for detecting peritoneal cancer
  • Laparoscopy is minimally invasive and allows for safe, directed peritoneal lavage
  • Open abdominal exploration and palpation are extremely sensitive for 1- to 2-mm peritoneal nodules

Studies for malignant peritoneal mesothelioma include the following:

  • Cytologic examination of ascites can suggest the diagnosis
  • Percutaneous biopsy of the omentum can help verify the diagnosis

Standard imaging tests, including ultrasonography and helical CT scans, are notably insensitive for the detection of peritoneal tumors. Ultrasonography findings that may suggest the presence of peritoneal lesions include the following:

  • Ascites
  • Fixing together of bowel loops
  • Thickening of mesentery
  • Omental matting

CT scan findings that suggest primary papillary serous carcinoma of the peritoneum include the following:

  • Ascites
  • Omental caking
  • Diffuse enhancement with nodular thickening of the parietal peritoneum of the pelvis
  • Normal-sized ovaries, with or without a fine enhancing surface nodularity of the ovary

CT findings in patients with malignant peritoneal mesotheliomas range from peritoneum-based masses (a so-called "dry" appearance) to ascites, irregular or nodular peritoneal thickening, and an omental mass (a so-called "wet" appearance). Scalloping of the peritoneum or direct invasion of adjacent abdominal organs may also be seen. [1]

Radionuclide scan studies can help confirm the diagnosis of peritoneal hemangiomas; the isotope concentrates in the area where platelets are being sequestered. A CT scan and ultrasound also may detect larger hemangiomas. Angiographic evaluation is a more precise, although invasive, procedure that may be considered when radionuclide scans, CT scans, and ultrasound findings are negative.

See Workup for more detail.

Management

Multimodality therapy is currently the most commonly accepted therapeutic approach for peritoneal mesothelioma. This includes using the combination of the following:

  • Surgical cytoreduction
  • Intraperitoneal perioperative chemotherapy
  • Hyperthermia

Heated chemotherapeutic drugs used intraoperatively include the following:

  • Cisplatin
  • Mitomycin
  • Doxorubicin

For patients with unresectable or recurrent malignant mesothelioma, palliative systemic chemotherapy should be considered. Palliative regimens may include the following:

  • Cisplatin plus pemetrexed
  • Cisplatin plus paclitaxel or mitomycin, doxorubicin, and irinotecan
  • Intraperitoneal instillation of radioactive colloidal gold (Au-198)

Primary peritoneal carcinoma is treated with tumor debulking followed by chemotherapy with 5-fluorouracil, doxorubicin, or cisplatin. Newer approaches include the following:

  • Taxanes, topoisomerase I inhibitors, gemcitabine, and vinorelbine, alone or in combinations
  • Adjunctive antiangiogenic drugs such as bevacizumab and erlotinib

Surgical care

  • Treatment of primary peritoneal carcinoma consists of total abdominal hysterectomy and bilateral salpingo-oophorectomy as needed, with debulking of tumor and follow-up chemotherapy
  • Treatment of malignant peritoneal mesothelioma consists primarily of surgical palliation; complete surgical resection is rarely, if ever, feasible
  • Benign cystic mesothelioma tends to recur even with aggressive surgical removal; however, among recorded cases, no deaths have been attributable to this disorder
  • In patients with desmoplastic small cell tumors, the combination of aggressive surgical debulking and systemic chemotherapy with cyclophosphamide, doxorubicin, and vincristine interspersed with ifosfamide, etoposide, and mesna (P6 protocol) appears to lead to an improved outcome
  • Treatment of peritoneal and GI hemangiomas has involved surgical removal

See Treatment and Medication for more detail.

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Background

The peritoneum is a serous lining of mesothelial cells with a rich vascular and lymphatic capillary network that covers the abdominal and pelvic walls and organs. Peritoneal neoplasia can originate de novo from the peritoneal tissues (primary) or invade or metastasize into the peritoneum from adjacent or remote organs (secondary).

A number of primary cancers have been described to originate from the peritoneum, some of which have been implicated in many cases of carcinomas of unknown primary origin. Ovarian cancer arising in women several years after bilateral oophorectomy is believed to be one of these primary peritoneal cancers. Other described primary peritoneal cancers and tumors include malignant mesothelioma, benign papillary mesothelioma, desmoplastic small round cell tumors, peritoneal angiosarcoma, leiomyomatosis peritonealis disseminata (LPD), and peritoneal hemangiomatosis.

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Pathophysiology

The peritoneal cavity, enclosed by visceral and parietal peritonea, is the largest potential space in the body. Any pathologic process involving the peritoneal cavity can easily disseminate throughout this space by means of unrestricted movement of fluid and cells.

Primary malignant diseases arising from the peritoneal cavity include malignant mesothelioma, cystic mesothelioma, primary peritoneal carcinoma, and desmoplastic small round cell tumor.

Malignant mesothelioma

Malignant peritoneal mesothelioma is a rare but aggressive tumor derived from the peritoneal mesothelium. Although most mesotheliomas involve the pleural surface, 20-30% arise from the peritoneum and are associated with asbestos exposure and abdominal therapeutic radiation. Association of malignant peritoneal mesothelioma and asbestos exposure has been reported to be as high as 83%.

Mesotheliomas are composed of strands of connective tissue covered by cells that react positively to periodic acid-Schiff staining in the cytoplasm. These cells grow in multiple layers, forming papillary or tubular formations. Histologically, malignant mesothelioma is classified into epithelial, sarcomatoid, and mixed. Clinical features of malignant mesothelioma include abdominal pain, abdominal or pelvic masses, and thrombocytosis; ascites is the major factor in the disease morbidity and mortality. Rarely, the tumor spreads into the pleural space.

On CT scan, this neoplasm can appear as peritoneum-based masses or abdominal ascites with associated nodular or diffuse peritoneal thickening.

This locally aggressive disease is difficult to treat or palliate. Commonly, treatment regimens combine aggressive cytoreductive surgery with intraperitoneal chemotherapy. Thorough cytoreductive surgery is the cornerstone of current treatment, while hyperthermic intraoperative intraperitoneal chemotherapy (HIIC) is a promising strategy in suitable patients. [2]

Cystic mesothelioma

Cystic mesothelioma is a rare intermediate-grade tumor with a predilection for surfaces of the pelvis. [3] Typically, these lesions consist of multiple grapelike clusters of mesothelium-lined cysts separated by fibrous tissue. The nomenclature for this entity is confusing, and several synonyms (eg, multilocular peritoneal inclusion cyst, cystic mesothelioma) are used interchangeably in the literature.

This rare tumor commonly occurs in young to middle-aged women and typically presents with abdominal pain, tenderness, or distension.

Radiologic tests demonstrate thin-walled cysts containing watery secretions, easily seen on ultrasound, CT scan, and MRI. [4]

Some authors reported effective intraperitoneal chemotherapy, but no clinical study is available about long-term outcome. The short-term prognosis is favorable, although the tumor recurs in 25–50% of cases.

The differential diagnosis includes lymphangioma, mesenteric-omental cysts, ovarian cystadenoma and cystadenocarcinoma, cystic teratoma, pseudomyxoma peritonei, cystic smooth muscle tumors, visceral cysts, and endometriosis.

Primary peritoneal carcinoma

Primary peritoneal carcinoma (ie, serous surface papillary carcinoma) arises primarily from peritoneal cells. The mesothelium of the peritoneum and the germinal epithelium of the ovary arise from the same embryologic origin; therefore, the peritoneum may retain the multipotentiality allowing the development of a primary carcinoma.

This rare malignancy predominantly affects postmenopausal women and typically displays multicentric peritoneal and omental involvement. Pathologically and clinically, it resembles papillary serous ovarian carcinoma. This malignancy is differentiated from its ovarian counterpart by the fact that it involves the extraovarian peritoneum significantly and the ovarian surface minimally or not at all. Extensive calcification or omental caking is present in many cases and is a useful CT finding to exclude mesothelioma. The absence of an ovarian mass is critical for excluding metastatic papillary serous ovarian carcinoma, which otherwise has a similar CT appearance.

Treatment of this malignancy is very similar to that of epithelial ovarian cancer, which includes combination chemotherapy after optimal cytoreductive surgery.

Desmoplastic small round cell tumor

This tumor is a highly aggressive malignancy that has recently been described. It involves the peritoneal cavity in most cases. Unlike the other primary peritoneal neoplasms, desmoplastic small round cell tumor (DSRCT) most often affects young adults. This malignancy extensively and rapidly invades the peritoneal surfaces with hematogenous metastasis to the liver, lungs, and lymph nodes.

Cytologically, DSRCT is a highly cellular tumor composed of small round cells with granular chromatin, nuclear molding, and inconspicuous nucleoli that are arranged singly and in clusters. [5] This tumor exhibits a unique immunohistochemical profile, characterized by coexpression of epithelial (keratin and epithelial membrane antigen), neural (neuron-specific enolase and CD56), mesenchymal (vimentin), and myogenic (desmin) markers. The reciprocal chromosomal translocation t (11; 22)(p13; q12) is also specific for DSRCT.

Radiological investigation shows multiple rounded peritoneal masses with or without ascites. The omentum and paravesical regions are often involved.

The recommended treatment is a combination of multiagent chemotherapy with adjuvant surgery and radiation. The overall survival for people with this disease is poor despite aggressive treatment.

Other neoplasms

Although clear cell carcinoma is often derived from the ovary and associated with endometriosis, cases of peritoneal origin have been reported. Residual tumor volume appears to determine survival in these patients. These tumors are typically resistant to conventional platinum-based chemotherapy but in one case, adjuvant chemotherapy using irinotecan and cisplatin was effective. [6]

In addition to the above-mentioned primary peritoneal malignancies arising from the peritoneal lining, various types of neoplasms may develop from mesenchymal and lymphatic tissues of the abdominal and pelvic cavities. This includes different forms of sarcomas, histiocytoma, [7] gastrointestinal stromal tumors (GIST), and lymphoproliferative malignancies. Moreover, the differential of peritoneal malignancies includes many benign tumors derived from lymphatic, vascular, neuromuscular, or fatty tissues.

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Frequency

United States

All of the primary peritoneal cancers are rare. Primary peritoneal carcinoma is very uncommon. Peritoneal mesotheliomas are also rare, with 2 cases per 1 million population reported each year. However, the incidence appears to be increasing. Based on the prior use of asbestos, more than 8 million people in the United States were exposed and at risk. Benign cystic peritoneal mesotheliomas are rare.

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Mortality/Morbidity

See the list below:

  • Survival is poor for patients with primary peritoneal carcinoma, with 100% mortality; the median survival reported is 12-25 months, even with extensive surgery and chemotherapy.
  • Benign cystic peritoneal mesotheliomas are associated with prolonged survival despite bulky disease.
  • Desmoplastic small round cell tumors are associated with a reported median survival of 17 months.

Sex

See the list below:

  • Primary peritoneal carcinoma is a rare tumor that occurs almost exclusively in women.
  • Malignant mesotheliomas show extreme male predominance (93% in one series).

Age

See the list below:

  • Primary peritoneal carcinoma occurs in older patients than do epithelial ovarian cancers.
  • Desmoplastic small round cell tumors occur in adolescent persons and young men.
  • Benign cystic peritoneal mesotheliomas are rare and are found predominantly in younger women.
  • Most cases of leiomyomatosis peritonealis disseminata have been discovered in reproductive-aged women (mean age 37 y), in young pregnant women, and in women who have hormonal excess for any other reason. In most reported cases, nodules either regress or exhibit growth once the hormonal stimulation has been removed.
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