Primary peritoneal cancer

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Synonyms and keywords: Primary peritoneal neoplasm; Primary peritoneal malignancy; Primary peritoneal tumors; Serous surface papillary carcinoma; Primary peritoneal carcinoma; Extra-ovarian serous carcinoma; Primary serous papillary carcinoma; Psammomacarcinoma

Overview

Primary peritoneal cancer is a cancer of the cells lining the peritoneum or abdominal cavity. Although the precise causes are not known, a link with certain variants of BRCA1/2 mutation has been described. Primary peritoneal cancer must be differentiated from asbestos, fibroids, pregnancy, pelvic inflammatory disease, and ovarian cyst. Primary peritoneal cancer commonly affects individuals older than 30 years of age. Females are more commonly affected with primary peritoneal cancer than males. Surgery is the primary treatment for extra-ovarian primary peritoneal carcinoma. The type of surgery done is surgical debulking. Surgical staging is done at the same time as debulking. Optimal tumor debulking followed by chemotherapy is the mode of treatment of primary peritoneal cancer.

Pathophysiology

• Primary peritoneal cancer is a cancer of the cells lining the peritoneum, or abdominal cavity. Some studies indicate that between 7 and 20 percent of initially diagnosed epithelial ovarian cancers could be properly reclassified as primary peritoneal cancers.

Classification

• Primary peritoneal neoplasms comprise of an uncommon group of heterogeneous entities that include:

• Mesothelial derivatives

• Primary (malignant) peritoneal mesothelioma
• Primary peritoneal multicystic mesothelioma
• Primary peritoneal well differentiated papillary mesothelioma
• Primary peritoneal adenomatoid tumor

• Epithelial derivatives

• Primary peritoneal serous carcinoma / primary peritoneal papillary serous carcinoma
• Primary peritoneal serous borderline tumor
• Smooth muscle cell derivatives
• Diffuse peritoneal leiomyomatosis (leiomyomatosis peritonialis disseminata)

• Others

• Desmoplastic small round cell tumor arising from the peritoneum
• Solitary fibrous tumor arising the abdomen/peritoneum
• Peritoneal lymphangioma

Pathogenesis

• Ovarian and peritoneal epithelium share common embryonal origin, which is the coelomic epithelium (mesodermal origin). Coelomic epithelium is thought to be of mesonephric origin. With the overall point being that normal ovarian and peritoneal tissue is derived from the mesonephros. On the contrary, fallopian tube epithelium, endometrium, and endocervix are related to paramesonephros (Müllerian duct). Surprisingly, epithelial ovarian cancer and primary peritoneal cancer are histologically similar to the mullerian epithelium; not their embryonal origin, the mesonephros. This observation suggests that either a metaplasia has occurred or Mullerian remnants have been left behind in coelomic epithelium, which has turned oncogenic.

Genetics

• Although the precise causes are not known, a link with certain variants of BRCA1/2 mutation has been described. Furthermore, women with BRCA1/2 mutation have a 5% risk of developing primary peritoneal cancer even after prophylactic oophorectomy.
• Primary peritoneal carcinoma shows similar rates of tumor suppressor gene dysfunction (p53, BRCA, WT1) as ovarian cancer and can also show an increased expression of HER-2/neu.
• An association with vascular endothelial growth factor has been observed.

Microscopic Pathology

Micrograph showing serous carcinoma. Peritoneal fluid specimen. Features: Marked intragroup nuclear pleomorphism. Macronucleoli. "Knobby" group borders (in large groups) - not apparent on the image. Hydropic vacuoles - not apparent on image

Causes

• The cause of primary peritoneal cancer has not been identified.

Differentiating Primary peritoneal cancer from other Diseases

• Primary peritoneal cancer must be differentiated from asbestos, fibroid, pregnancy, pelvic inflammatory disease, and ovarian cyst.

Demographics

Age

• Primary peritoneal cancer commonly affects individuals older than 30 years of age.

Gender

• Females are more commonly affected with primary peritoneal cancer than males.

Natural History, Complications and Prognosis

• Primary peritoneal cancer is associated with a particularly poor prognosis. Median survival period is 12-25 months.

Diagnosis

Staging

• Primary peritoneal cancer may be classified into 2 subtypes based on extent of spread namely stage 3 and stage 4.

Symptoms

• Ascitis
• Weight loss
• Abdominal mass
• Abdominal pain
• Indigestion
• Nausea
• Shortness of breath

Physical Examination

Appearance of the Patient

• Patients with primary peritoneal cancer usually appear cachetic.

Abdomen

• The presence of a large ill defined anterior abdominal mass on physical examination is suggestive of primary peritoneal cancer.

Lab Findings

• Elevated albumin levels have been detected among patients with primary peritoneal cancer.

Treatment

• Prognosis and treatment is the same as for epithelial ovarian cancers.
• Optimal tumor debulking followed by chemotherapy is the mode of treatment of primary peritoneal cancer.

Pharmacotherapy

• Preferred regimen: Paclitaxel 135 mg/m2 IV over 24 h on day 1 AND cisplatin 100 mg/m2 IP on day 2 AND paclitaxel 60 mg/m 2 IP on day 8 for 21 days for 6 cycles.(1)
• Preferred regimen (2): (Paclitaxel 135-175 mg/m2 IV infused over 3 hours AND carboplatin AUC 5-7.5 IV infused over 30-60 min every 21 days for three to six cycles) OR (Docetaxel 60-75 mg/m 2 IV infused over 1 hour) AND carboplatin AUC 5-6 IV infused over 1 hour every 21 days for three to six cycles

Platinum-sensitive disease

• Preferred regimen(1): Paclitaxel 135-175 mg/m2 IV infused over 3 hours AND carboplatin AUC 5-6 IV infused over 1 hour every 21 days for six cycles
• Preferred regimen(2): Docetaxel 60-75 mg/m2 IV infused over 1 hour AND carboplatin AUC 5 IV infused over 1 hour every 21 days for three to six cycles
• Preferred regimen(3): Pegylated liposomal doxorubicin 30 mg/m2 IV infused over 30 min AND carboplatin AUC 5 IV every 21 days for six cycles
• Preferred regimen(4): Gemcitabine 1000 mg/m2 IV on days 1 and 8 AND carboplatin AUC 4 on day 1 every 21 days for six cycles

Note: Bevacizumab (15 mg/kg every 3 wk) may be added to the regimen

• Preferred regimen(5): Carboplatin AUC 2 IV push with paclitaxel 80 mg/m2 IV infused over 3 hours on days 1, 8, and 15

Platinum-resistant disease

• Preferred regimen(1): Pegylated liposomal doxorubicin 50 mg/m2 IV infused over 30 min every 21 days
• Preferred regimen(2): Topotecan 1.25 mg/m2 IV infused over 30 min on days 1-5 every 21 days
• Preferred regimen(3): Gemcitabine 1000 mg/m2 IV infused over 30 min on days 1 and 8 every 21 days

Combination Regimen

• Bevacizumab 10 mg/kg IV every 14 days in combination with one of the following IV chemotherapy regimens: paclitaxel, pegylated liposomal doxorubicin, or topotecan (topotecan is given weekly)
• Bevacizumab 15 mg/kg IV every 21 days in combination with topotecan (every 21 days)

Surgery

• Surgery is the primary treatment for extra-ovarian primary peritoneal carcinoma. The type of surgery done is surgical debulking. Surgical staging is done at the same time as debulking.