Primary peritoneal cancer (PPC) is a rare malignancy arising from the peritoneal lining.
- Histologically and clinically similar to epithelial ovarian cancer, particularly high-grade serous carcinoma.
- Tumor originates in the peritoneum rather than the ovary, though the ovaries may appear normal or minimally involved.
Epidemiology
- More common in postmenopausal women.
- Incidence is lower than ovarian cancer but clinically behaves similarly.
- Often diagnosed at advanced stage due to nonspecific abdominal symptoms.
Pathogenesis
- High-grade serous histology is most common.
- Frequently associated with BRCA1/2 mutations or homologous recombination deficiency (HRD).
- Molecular profile often mirrors high-grade serous ovarian carcinoma.
Clinical Features
- Abdominal bloating, pain, or distension
- Ascites and early satiety
- Weight loss and fatigue
- Symptoms are often insidious, leading to late-stage diagnosis
Diagnostics
- Imaging: CT scan of abdomen and pelvis to detect peritoneal thickening, nodules, or ascites
- Tumor markers: CA-125 often elevated
- Histopathology: Confirms serous carcinoma of peritoneal origin
- Genetic testing: BRCA1/2, HRD for therapeutic guidance
Treatment (Oncology Pharmacy Focus)
Surgery
- Cytoreductive surgery (debulking)
- Goal: no gross residual disease
- Ovaries may be removed if involved or prophylactically
Chemotherapy
- Platinum + taxane regimen (Carboplatin + Paclitaxel), similar to ovarian cancer
- Intraperitoneal chemotherapy may be considered in select cases
Targeted / Maintenance Therapy
- PARP inhibitors (Olaparib, Niraparib, Rucaparib) for BRCA-mutated or HRD-positive tumors
- Anti-angiogenic therapy (Bevacizumab) may be used as maintenance or with chemotherapy
Supportive Care
- Anti-emetics, growth factor support if myelosuppression occurs
- Ascites management: paracentesis or diuretics
- Thromboprophylaxis due to high VTE risk
Prognosis
- Dependent on residual tumor after surgery, stage at diagnosis, and molecular profile
- Survival and treatment response are generally similar to high-grade serous ovarian cancer