Peritoneal Neoplasm

Peritoneal neoplasm is a rare cancer that affects the peritoneum, a thin membrane lining the abdomen and covering the organs inside it. Most people don’t notice symptoms until the disease has progressed to a later stage, making early detection challenging. Treatment typically involves surgery combined with specialized chemotherapy, offering hope for improved survival and quality of life.

Table of contents

• What is peritoneal neoplasm?
• Types of peritoneal neoplasm
• Associated anatomy
• Who is at risk?
• Signs and symptoms
• Diagnosis
• Treatment options
• What to expect

What is peritoneal neoplasm?

Peritoneal neoplasm is a cancer that develops in the peritoneum, a thin, delicate layer of tissue that lines the inside of the abdomen and covers the organs within it^[1]. The peritoneum is made of epithelial cells, which are cells that protect surfaces of the body. This membrane also produces a fluid that helps organs move smoothly inside the abdomen^[4].

When cells in the peritoneum begin to grow abnormally and uncontrollably, they form tumors^[1]. This cancer can spread across the abdominal lining and affect the surface of any organ contained within it^[5].

Peritoneal neoplasm is very rare. Providers diagnose fewer than 7 in 1 million cases each year^[1]. However, researchers estimate that up to 15% of women diagnosed with advanced ovarian cancer may actually have peritoneal cancer^[1].

Types of peritoneal neoplasm

Healthcare providers classify peritoneal cancer based on where it first occurs^[1]:

Primary peritoneal cancer starts inside the cells that make up the peritoneum itself. It originates within the peritoneum rather than spreading from other parts of the body^[1]. This type is also known by several names, including extraovarian primary peritoneal carcinoma, serous surface papillary carcinoma, and papillary serous carcinoma of the peritoneum^[2].

Secondary peritoneal cancer starts elsewhere in your body and spreads to the peritoneum. This happens when cancer from a different organ travels to the peritoneum and forms tumors there^[1]. It is also called peritoneal carcinomatosis^[3]. The primary cancers most likely to lead to secondary peritoneal cancer include ovarian cancer, colon cancer, stomach cancer, pancreatic cancer, appendix cancer, and rectal cancer^[21].

Additional types of peritoneal cancer include malignant peritoneal mesothelioma, multicystic mesothelioma, and desmoplastic small round cell tumor^[2].

Associated anatomy

• Peritoneum (abdominal lining)
• Bladder
• Intestines
• Rectum
• Uterus
• Stomach
• Colon
• Ovaries

Who is at risk?

Women have a higher risk of primary peritoneal cancer than men^[1]. Most people diagnosed with primary peritoneal cancer are age 60 and older^[1]. The risk factors for peritoneal cancer are similar to those for ovarian cancer^[1].

Several factors can increase a person’s risk of developing peritoneal neoplasm:

Genetics plays a significant role. Having a first-degree family member such as a mother, sister, or daughter with peritoneal cancer, fallopian tube cancer, or ovarian cancer increases your risk^[1]. Women with BRCA1 or BRCA2 gene mutations have a higher risk^[1]. People with genes for Lynch syndrome, a hereditary condition that raises the risk of several types of cancers, also face increased risk^[1].

Endometriosis increases risk. This is a condition when tissue similar to cells that line the uterus grows outside of the uterus^[1].

Hormone replacement therapy taken after menopause has been associated with increased risk^[1].

Other risk factors include obesity (people with a higher amount of body fat have a higher risk), being taller in height, and reproductive history such as infertility or having no biological children^[1].

It’s important to note that researchers don’t know exactly why some people develop primary peritoneal cancer. People born with certain gene mutations have a higher risk of the disease^[1].

Signs and symptoms

People often don’t notice symptoms in the early stages of peritoneal cancer. As a result, most people are diagnosed with peritoneal cancer at a later stage^[1]. The initial symptoms, when present, are generally vague and can resemble those of other conditions^[3].

Symptoms often become more noticeable when cancer cells grow and start affecting nearby organs, such as the intestines, bladder, and stomach^[3]. Many of these symptoms are due to fluid buildup in the abdomen called ascites^[4].

The most common symptoms include:

• Abdominal swelling or bloating. This is the most common symptom. Swelling is caused by fluid buildup in the belly. Someone may feel that they are gaining weight in the belly despite exercise^[3].
• Abdominal pain or discomfort. This is often described as vague cramping or pressure-like pain. It may feel like gas, indigestion, pressure, or cramps^[1].
• Loss of appetite. Someone may feel full quickly, even after small meals^[3].
• Unexplained weight loss or weight gain with no known reason^[4].
• Fatigue. Someone may feel very tired, even after resting^[3].
• Nausea and vomiting. These are often linked to bowel issues caused by tumor pressure^[3].
• Bowel changes. These can include constipation or diarrhea^[3].
• Frequent urination^[4].

As the disease progresses, there may be other symptoms such as a palpable abdominal mass, abnormal vaginal bleeding, rectal bleeding, and shortness of breath^[4].

Diagnosis

To diagnose peritoneal cancer, your doctor will begin by asking about any symptoms you may have. They will also review your medical history and conduct a thorough physical exam^[1]. The physical examination involves checking for abnormalities in the uterus, vagina, ovaries, fallopian tubes, bladder, stomach, colon, and rectum^[4].

Several tests may be used to diagnose peritoneal neoplasm:

Imaging tests are typically the first step. These may include CT scan, MRI, and PET scan or a combination of these^[21]. These scans help identify visible tumor spread, fluid buildup, or organ involvement^[9]. A CT scan creates a series of detailed pictures of areas inside the body using a computer linked to an X-ray machine^[4].

Ultrasound uses high-frequency sound waves to produce a picture called a sonogram^[4]. This test may be performed on the abdomen or pelvis^[8].

Blood tests may be ordered to check for tumor markers. The CA-125 blood test measures the level of CA-125, a tumor marker that is often found in higher-than-normal amounts in the blood of women with ovarian cancer or peritoneal cancer^[4]. However, CA-125 can be high for other reasons, so this test cannot confirm a diagnosis of these cancers^[4].

Paracentesis may be performed if you have ascites. Your provider may remove a sample of the fluid in your abdomen and test it in a lab for signs of cancer^[21]. This test checks for cancer cells floating in the peritoneal fluid^[9].

Biopsy involves removing a sample of tissue or tumor and testing it in a lab for cancer cells^[21]. This helps confirm the presence of cancer and determine its type.

Staging laparoscopy is a safe, minimally invasive surgical procedure used to look directly inside the abdominal cavity using a small camera. It allows healthcare professionals to inspect the peritoneum, find hidden tumors, and take tissue or fluid samples^[9].

During the diagnostic process, your healthcare provider may use the Peritoneal Carcinomatosis Index (PCI). This is a scale used to assess the tumor burden in the peritoneum^[12]. Using this index, providers map the location of the tumor in your abdomen and your small intestine and assign a score based on the tumor’s size^[21].

Treatment options

The first treatments for peritoneal cancer tend to be surgery followed by chemotherapy or targeted therapy^[1]. Treatment depends on the stage of cancer, where the primary tumor started, how far it has spread, and the patient’s overall health^[10].

Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) is the standard treatment for peritoneal cancer. The goal of cytoreductive surgery, also called debulking surgery, is to remove all visible tumors in the peritoneum^[21]. This operation removes all visible cancer in the abdominal cavity, including any visible peritoneal tumors^[10].

After removing the tumors, the surgeon administers a heated chemotherapy solution, about 107 degrees Fahrenheit, into the abdominal cavity, where it is gently agitated for 90 minutes^[10]. Heating the chemotherapy solution improves absorption by tumor cells that might remain in abdominal tissue^[10]. This treatment can control symptoms, prevent cancer from coming back, and, in some cases, even cure the cancer^[10].

The operation takes six to nine hours, and the average hospital stay after the procedure is seven to 14 days^[10]. HIPEC greatly enhances drug concentrations in the peritoneal cavity and decreases its systemic toxicity^[13].

Chemotherapy uses cancer-fighting medications to destroy cancer cells that have spread to other parts of the body^[10]. The first-line chemotherapy regimen for peritoneal cancer is a platinum agent with a taxane^[13]. Chemotherapy is sometimes used before or after surgery^[10].

Targeted therapy uses cancer-fighting medications that can attack specific abnormalities in or on cancer cells or can boost the immune system to attack cancer cells^[10]. Medical oncologists first test a patient’s cancer cells to find out whether a specific targeted therapy might work. If patients are found to have BRCA1 or BRCA2 mutations, olaparib maintenance therapy is recommended^[13]. Targeted therapy can be a treatment option for some patients with advanced primary peritoneal cancer^[10].

Radiation therapy is a noninvasive treatment that uses high-energy radiation beams to destroy cancer cells^[10]. It is sometimes recommended for patients with advanced primary or recurrent peritoneal cancer^[10].

Immunotherapy uses drugs to stimulate the immune system to fight cancer^[6]. Immune checkpoint inhibitors have been incorporated into treatment regimens for various solid tumors, including mesothelioma^[13].

At specialized medical centers, patients benefit from the expertise of a full multidisciplinary team evaluating each patient’s situation and working together to determine the best course of treatment^[10].

What to expect

Peritoneal cancer is usually diagnosed at a later stage because symptoms often don’t appear until the cancer has progressed^[1]. People diagnosed with peritoneal cancer are usually older than those diagnosed with ovarian cancer. The prognosis for peritoneal cancer is also worse than that of ovarian cancer^[1].

Secondary peritoneal cancer (peritoneal carcinomatosis) is usually a sign that the cancer is at a late stage^[3]. Cancers that have spread, like peritoneal carcinomatosis, are also called late-stage or metastatic cancers. They’re usually more serious than early-stage cancers. But treatments can help slow disease progression and help you live longer^[21].

While the median survival with traditional therapeutic options ranges from 4 to 12 months, the application of multimodality therapy has shown promising results with increased survival approaching 60 months^[13]. The introduction of cytoreductive surgery with HIPEC has significantly improved the life expectancy of patients with peritoneal cancer^[12].

Prognosis varies depending on factors like the stage of cancer, histological subtype, and patient’s overall health, with early detection and multimodal treatment offering the best chances for improved outcomes^[2].

As peritoneal cancer progresses, complications may include bowel obstructions (sometimes necessitating a stoma, or hole between the intestine and the outside of the body), and urinary tract obstruction due to blockage of the ureters by tumors, sometimes requiring a stent or nephrostomy tube^[6].