Primary Peritoneal Cancer
Overview
Primary peritoneal cancer is a rare cancer that starts in the peritoneum, the thin membrane that lines the inside of the abdomen and covers organs like the stomach, liver, and intestines. Because the peritoneum and the surface of the ovaries are made of the same type of cells, this cancer closely resembles epithelial ovarian cancer and is treated the same way. It occurs almost exclusively in women, is more common as people age, and is often diagnosed after ovarian cancer has been ruled out. A separate and less common cancer that affects this lining is peritoneal mesothelioma, which is typically linked to asbestos exposure.
Signs & Symptoms
Primary peritoneal cancer often develops slowly, and symptoms may be vague at first. As the cancer grows, women may notice:
- Abdominal bloating or swelling
- Loss of appetite or feeling full quickly
- Nausea or indigestion
- Unexplained weight gain or weight loss
- Pelvic or lower abdominal pain
- Changes in bowel habits such as constipation or diarrhea
- Needing to urinate more often
- Swelling in the abdomen caused by fluid buildup (ascites)
These symptoms can be caused by many conditions, but if they are persistent or worsening over several weeks, it is important to contact your primary care provider.
Causes & Risk Factors
The exact cause of primary peritoneal cancer is unknown. Factors that may increase risk include:
- Age: The disease is more common in older women.
- Inherited Genetic Changes: Some cases are linked to inherited gene mutations that also increase the risk of breast and ovarian cancer, such as BRCA1 or BRCA2.
- Endometriosis: Having endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus, may increase the risk of developing primary peritoneal cancer.
- Family History: A family history of ovarian or related cancers may increase risk.
- Gender: Primary peritoneal cancer occurs almost exclusively in women.
Most cases develop without a clear risk factor, and having a risk factor does not mean someone will develop the disease.
Diagnosing Primary Peritoneal Cancer
Evaluation typically begins with your primary care provider, who may order initial blood work or imaging. If symptoms or test results suggest a peritoneal or ovarian cancer, you may be referred to a gynecologic specialist for further testing. Common diagnostic tests include:
An abdominal or pelvic ultrasound uses sound waves to create images of the abdomen and pelvis. A vaginal ultrasound may also be used to get a closer look at the ovaries and surrounding tissue.
A CT scan takes detailed cross-sectional images of the abdomen. A contrast dye may be used to highlight areas of concern.
MRI creates detailed images using magnetic fields and can help assess organs, lymph nodes, and surrounding structures.
Blood tests may include checking CA-125, a protein that can be elevated in primary peritoneal or ovarian cancer.
If there is fluid buildup (ascites), a sample may be taken and examined for cancer cells.
A minimally invasive procedure where a small camera is inserted into the abdomen to evaluate organs directly and take tissue samples.
In some cases, a larger surgical procedure may be needed to confirm the diagnosis and fully evaluate the abdomen.
Staging Primary Peritoneal Cancer
Primary peritoneal cancer is staged using the same system as epithelial ovarian cancer because the two diseases behave almost identically. However, PPC is only diagnosed once ovarian cancer has been ruled out, and the disease is already present on the peritoneal lining. For this reason, PPC is never classified as stage 1 or stage 2.
Instead, cases are staged as stage 3 or stage 4, depending on how far the cancer has spread within the abdomen or to distant organs.
| Stage | Description of Stage |
|---|---|
| Stage 3 | Cancer is present on the peritoneum within the abdomen |
| Stage 4 | Cancer has spread outside the abdomen, such as to the liver, lungs or distant lymph nodes |
Treatments & Services
Treatment Options
Treatment for primary peritoneal cancer is very similar to treatment for epithelial ovarian cancer. Care plans are personalized based on the extent of disease, overall health, and whether surgery is appropriate.
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If you have symptoms or a diagnosis of primary peritoneal cancer, our team is here to help. We connect you with specialists who can provide the right tests, discuss treatment options, and support you every step of the way. Early evaluation and coordinated care can make a meaningful difference
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