Understanding Primary Peritoneal Cancer: What You Need to Know About This Rare Abdominal Condition

Have you ever heard the name primary peritoneal cancer before? You might not have, because it is a relatively rare type of cancer. However, learning about this condition is very important, especially for women. Today, let us talk about this topic in a simple way that is easy for you to understand.

Cancer can affect different parts of the body in unexpected ways. When it starts in the thin lining inside your belly, it requires specialized medical care. Knowing what to watch for can help you seek medical advice early.

What Is Primary Peritoneal Cancer?

Simply put, primary peritoneal cancer is a cancer that forms in the thin tissue lining the inside of your belly or abdominal cavity. We call this lining the peritoneum. Think of it like a protective inner lining inside a balloon.

This peritoneum lining also covers several important organs inside your belly. Examples of these organs include:

• Your bladder.
• Your intestines.
• Your rectum.
• Your uterus (in women).

Did you know that the peritoneum is made of special cells called epithelial cells? These cells help protect different surfaces in your body. Also, the peritoneum produces a special fluid. This fluid allows the organs inside your belly to move freely without rubbing against each other.

Therefore, primary peritoneal cancer develops when these cells in the peritoneum start to grow abnormally and without control. Now let us look at the types of peritoneal cancer. Doctors divide this into two types based on where the cancer starts:

1. Primary peritoneal cancer: In this type, the cancer starts right in the cells that make up the peritoneum. We are mainly focusing on this type today.

2. Secondary peritoneal cancer: In this case, cancer starts somewhere else in your body (such as your ovaries, stomach, or bowels) and then spreads to the peritoneum. This means it did not start in the peritoneum itself.

How Common Is Primary Peritoneal Cancer?

Actually, primary peritoneal cancer is a very rare type of cancer. Think about it this way: fewer than 7 people out of a million are diagnosed with this disease each year. However, these statistics might not show the full picture. Some researchers believe that about 15% of women diagnosed with advanced ovarian cancer actually have peritoneal cancer. This happens because the symptoms of both conditions are very similar.

Who Is at Higher Risk?

Women have a higher risk of getting primary peritoneal cancer than men. The risk factors for this condition are very similar to the risk factors for ovarian cancer. Let us look at what they are:

• Age: Doctors usually diagnose this condition in people aged 60 or older.
• Endometriosis: If you have endometriosis (a condition where tissue similar to the lining of the uterus grows outside the uterus), your risk may be higher.
• Family history and genetics: If a close family member (mother, sister, daughter) has had peritoneal cancer, fallopian tube cancer, or ovarian cancer, your risk is higher. Also, women with BRCA1 or BRCA2 gene mutations have an increased risk. People with genes related to Lynch syndrome (an inherited condition that increases the risk of several cancers) also face a higher risk.
• Height: Taller people appear to have a slightly higher risk of developing this cancer.
• Hormone replacement therapy: Women who take hormone therapy after menopause may have a higher risk.
• Obesity: People who carry extra body fat also face a higher risk.
• Reproductive history: people having infertility and/or those who have not had children may have a slightly increased risk.

What Is the Difference Between Peritoneal Cancer and Ovarian Cancer?

This is a place where many people get confused. The place where peritoneal cancer starts is different from where ovarian cancer starts. Ovarian cancer usually starts inside the ovaries or in the cells at the end of the fallopian tubes. However, peritoneal cancer develops in the cells of the peritoneum, the membrane that lines the inside of the abdomen and covers the abdominal organs, as mentioned before.

These two cancers are easily confused because both the peritoneum and the tissue covering the ovaries are made of the same type of cells (epithelial cells). Also, because both cancers spread along the inner lining of the abdomen, it is sometimes hard to figure out exactly where the cancer started.

Usually, people diagnosed with peritoneal cancer are older than those diagnosed with ovarian cancer. Also, the outlook or prognosis for peritoneal cancer can sometimes be more challenging than for ovarian cancer.

Why Does Primary Peritoneal Cancer Happen?

Actually, researchers still have not been able to figure out exactly why some people get primary peritoneal cancer. However, as mentioned earlier, they have discovered that people born with certain gene mutations have a higher risk of developing this disease.

What Are the Symptoms?

Just like ovarian cancer, this condition shows very few symptoms in the early stages. Even if symptoms are present, they are often vague or similar to signs of other common health issues. Most people notice symptoms only after the cancer has progressed or spread.

However, if someone does experience symptoms early on, they might look like this:

• Pain in the abdomen and/or lower belly.
• Unusual vaginal bleeding or discharge.
• Feeling bloated or feeling heaviness in the belly or lower belly.
• Changes in bowel habits (constipation and/or increased gas) or bleeding from the rectum.
• Needing to urinate often.
• Indigestion, loss of appetite, or feeling full quickly after eating a small amount of food.
• Gaining or losing weight without trying.

As peritoneal cancer grows, more symptoms can appear. These include:

• Severe fatigue.
• Fluid buildup in the belly (this is called ascites).
• Nausea or vomiting.
• Difficulty breathing (dyspnea).
• Swelling in the legs.

What Are the Complications?

People with advanced peritoneal cancer may experience complications such as:

• Severe abdominal pain.
• Inability to eat or drink properly.
• Severe nausea or vomiting.
• Small bowel obstruction, large bowel obstruction, or urinary tract obstruction.

How Is This Condition Diagnosed?

When you visit a doctor, they will first ask about your symptoms and perform a physical exam. If your symptoms suggest this could be peritoneal cancer, they may recommend tests such as:

• Blood tests: These tests check for a chemical called CA-125 produced by some cancer cells. People with peritoneal cancer may have elevated CA-125 levels. Doctors may also check if a protein called HE4 (which can also be produced by peritoneal cancer cells) is elevated.
• Imaging tests: Tests like an ultrasound, MRI, or CT scan check for cancerous growths. However, finding peritoneal cancer with these tests can sometimes be difficult.
• Laparoscopy: To confirm the diagnosis, your doctor may perform a laparoscopy. This involves making very small cuts in your belly and inserting a camera-equipped tool to look inside. During this procedure, the doctor can take a small sample of abnormal tissue (called a biopsy). A pathologist (a specialist doctor who examines tissues) then examines it under a microscope to confirm if cancer is present.
• Paracentesis: If you have fluid built up in your belly (ascites), your doctor can take a sample of that abdominal fluid and test it. Doctors often perform this paracentesis during the laparoscopy procedure.
• Pelvic exam: This examines your vagina, cervix, uterus, fallopian tubes, ovaries, and rectum to check for unusual lumps or areas.

Let Us Also Learn About Special Tests.

If you have certain conditions, your doctor may refer you to a genetic counselor to discuss genetic conditions linked to a higher risk of peritoneal cancer:

• If a close family member (mother, sister, daughter) has had peritoneal cancer, fallopian tube cancer, or ovarian cancer.
• If anyone in your family has BRCA1 or BRCA2 gene mutations.
• If anyone in your family has Lynch syndrome.

What Are the Stages of This Cancer?

Because primary peritoneal cancer often does not cause symptoms in its early stages, doctors usually diagnose it in stage 3 or stage 4.

• Stage 3: The cancer has spread outside the pelvic cavity or to lymph nodes at the back of the abdomen.
• Stage 4: The cancer has spread to organs outside the abdomen (such as the lungs, liver, or spleen) or to the membrane lining the lungs and chest.

How Is It Treated and Managed?

The treatment approach for primary peritoneal cancer depends on several factors:

• The size and location of the cancerous tumor.
• The stage of the cancer.
• Your age and overall health status.

Doctors often use surgery as the primary treatment. You may undergo a surgery called cytoreductive surgery. The goal of this surgery is to remove as much cancer tissue as possible. Research shows that results are better when a gynecologic oncologist (a specialist doctor who treats diseases and cancers of the female reproductive system) performs this surgery.

The surgeon may also remove items such as:

• Fallopian tubes and ovaries (this is called an oophorectomy).
• The uterus (this is called a hysterectomy).
• The fatty tissue around your bowels, known as the omentum (this is called an omentectomy).
• Other abnormal tissues.

To stop cancer cells from spreading to other parts of your body, your treatment plan may include:

• Chemotherapy: Traditional chemotherapy for peritoneal cancer is given through a vein (intravenous) or directly into the abdominal cavity (intraperitoneal). In some cases, doctors use heated chemotherapy drugs (called Hyperthermic Intraperitoneal Chemotherapy - HIPEC). This HIPEC treatment is given right after cytoreductive surgery while you are still asleep under anesthesia in the operating room, by infusing it into the abdominal cavity. This HIPEC method can be more effective for treating certain cancers.
• Targeted therapy: Doctors may use special drugs that target cancer cells directly without harming normal cells.
• Hormonal therapy: In advanced cases, doctors sometimes combine hormonal therapy with chemotherapy. This treatment works by stopping your body's natural hormones from reaching cancer cells and slowing their growth.
• Radiation therapy: Radiation therapy is rarely used as a first treatment for peritoneal cancer. If the cancer returns after initial treatments and is limited to a small area, doctors may use radiation therapy.

How Can I Lower My Risk?

Doing these things may help slightly lower your risk of developing primary peritoneal cancer:

• Breastfeeding children.
• Giving birth to children.
• Taking birth control pills.
• Having your fallopian tubes and/or ovaries removed surgically.
• Having your fallopian tubes tied (tubal ligation).

Some people with a family history of ovarian cancer or BRCA gene mutations, who face a higher risk of peritoneal cancer, choose to have their ovaries and fallopian tubes removed. Keep in mind that while this surgery reduces the risk of peritoneal cancer, it does not eliminate it completely.

What Is the Outlook? (Prognosis).

Because peritoneal cancer is usually diagnosed at a later stage, the outlook (prognosis) can be challenging. The cancer can also return after treatment. However, detecting the disease early helps improve outcomes.

About half of the people with peritoneal, fallopian tube, or ovarian cancer live for five years or more after diagnosis. Relatively younger people tend to live longer. This the outlook for older adults can be more challenging.

Survival rates can improve in these situations:

• If the cancer has not spread to your lymph nodes.
• If you have received HIPEC treatment.
• If the surgeon has removed as much cancer as possible.

Several clinical trials are currently underway to find new ways to treat peritoneal cancer. These new treatments include targeted therapies and immunotherapy. Immunotherapy works by stimulating your own immune system to recognize and attack cancer cells inside your body.

How Should I Take Care of Myself?

To help manage symptoms caused by advanced peritoneal cancer, your doctor may suggest meeting with a palliative medicine provider (a medical field focused on easing and addressing symptoms of serious illnesses). Your care may include:

• Reducing nausea and vomiting.
• Nutritional counseling for loss of appetite and meal recommendations.
• Pain management.
• Paracentesis to remove fluid built up in your belly (ascites).

How Can I Cope Well With This Condition?

Joining a support group with other people receiving treatment can help you feel like you are not alone. These support groups can also help your family members better understand the situation you are facing.

The Most Important Takeaway to Take Home.

Primary peritoneal cancer is a rare type of cancer that forms in the lining inside your belly. Symptoms often show up only after the cancer has progressed, which is why it is usually diagnosed at a later stage. However, outcomes can improve with advanced treatment options like HIPEC, targeted therapies, and surgery. also, clinical trials are ongoing to discover more treatment options that can help increase survival rates.

The most important thing is that if you continue to have the symptoms mentioned earlier (especially unusual changes in the belly, pain, or a feeling of heaviness), please seek medical advice. Detecting it earlier means treatments are more likely to be successful.

Sources & References:

• Cleveland Clinic. Primary Peritoneal Cancer: Causes, Symptoms & Treatment. Available online.
• Mayo Clinic. Primary Peritoneal Cancer - Diagnosis and Treatment Overview. Available online.
• National Health Service (NHS UK). Ovarian and Peritoneal Cancer Information. Available online.
• Centers for Disease Control and Prevention (CDC). Gynecologic Cancers Overview. Available online.
• National Institutes of Health (NIH / PubMed). Clinical Studies on Cytoreductive Surgery and HIPEC in Peritoneal Malignancies.