Primary Peritoneal Carcinoma: What It Is, How It's Diagnosed, and Current Treatment Approaches

Primary peritoneal carcinoma (PPC) is a rare cancer of the abdominal lining that behaves like high-grade serous ovarian cancer. It typically causes vague abdominal symptoms and is diagnosed with imaging, tumor markers, and tissue biopsy. Standard treatment is cytoreductive surgery plus platinum-based chemotherapy; targeted options such as PARP inhibitors and anti-angiogenic agents may be used based on genetic testing. Prognosis varies with stage and residual disease; PPC is not uniformly fatal.

What is primary peritoneal carcinoma?

Primary peritoneal carcinoma (PPC) is a rare cancer that arises from the peritoneum, the thin tissue that lines the abdominal cavity and covers abdominal organs. PPC behaves like epithelial (serous) ovarian cancer because the peritoneal lining and the ovarian surface share developmental and histologic features. Clinically, physicians usually manage PPC the same way they manage high-grade serous ovarian cancer.

How it presents

Early symptoms are often vague. Common complaints include abdominal bloating or swelling, pelvic or abdominal pain, early fullness after eating, and unexplained weight loss. Ascites (fluid in the abdomen) can develop and lead to more noticeable swelling.

How it is diagnosed

Diagnosis starts with a clinical exam and imaging, most often CT of the abdomen and pelvis. Blood tests may show an elevated CA-125 tumor marker, but this is not specific. Definitive diagnosis requires tissue: laparoscopy or image-guided biopsy and pathology show serous carcinoma involving peritoneal surfaces. Because PPC mimics ovarian cancer, pathology and immunohistochemistry are important to distinguish primary peritoneal origin from metastatic disease.

Genetic testing (germline and tumor) is recommended because BRCA1/2 mutations and other homologous recombination defects are found in a subset of cases and influence treatment choices.

Treatment today

Treatment mirrors that for advanced epithelial ovarian cancer. Standard first-line therapy combines cytoreductive (debulking) surgery to remove as much visible tumor as possible with platinum-based chemotherapy, typically a platinum agent plus a taxane.

Targeted therapies now play a larger role. Patients with BRCA mutations or homologous recombination deficiency may benefit from maintenance therapy with PARP inhibitors after initial chemotherapy. Anti-angiogenic agents (for example, bevacizumab) may be used in selected patients. Hyperthermic intraperitoneal chemotherapy (HIPEC) is used in some peritoneal surface malignancies and is under investigation or selectively applied for peritoneal carcinomatosis, but its routine role in PPC is limited and remains institution-dependent.

Prognosis and follow-up

Prognosis depends on stage at diagnosis, tumor biology, and the amount of residual disease after surgery. PPC is not universally fatal; outcomes vary and have improved with modern chemotherapy and targeted agents. Close follow-up includes clinical assessment, CA-125 monitoring when appropriate, and periodic imaging.

Special considerations

PPC can (rarely) arise even after removal of the ovaries and fallopian tubes, so risk-reducing surgery does not entirely eliminate the possibility of peritoneal carcinoma. Genetic counseling is recommended for patients and at-risk family members.

When to seek care

See a doctor if you have persistent abdominal bloating, unexplained pelvic or abdominal pain, decreased appetite, or unexplained weight changes. Early evaluation improves the chance for accurate diagnosis and timely treatment.

1. Confirm current consensus and guideline statements on the routine use of HIPEC for primary peritoneal carcinoma versus selective/investigational use.
2. Verify regulatory approvals and guideline-recommended indications for PARP inhibitors specifically in primary peritoneal carcinoma (as opposed to ovarian carcinoma) in major jurisdictions.