The Omentum and Metastatic Ovarian Cancer

Over half of ovarian cancer cases are diagnosed when it has metastasized (spread to distant organs). One of the structures it may spread to is the omentum, a layer of fatty tissue that hangs off the middle of your colon and drapes over the intestines inside the abdomen. When this occurs, it is referred to as ovarian cancer metastatic to the omentum.

Cancer may also originate in the omentum, where it is referred to as primary omentum cancer. Even so, this type of cancer is exceptionally rare, and most cases involving the omentum are metastatic.

What Is the Omentum?

The omentum is a two-layered structure that covers and surrounds the organs of the abdominal cavity like a parachute. Its consistency is somewhere between that of lumpy linen and gelatin.

The omentum is broken down into two parts, which in adults are mostly fused together:

• The greater omentum, which hangs down from the stomach
• The lesser omentum, which hangs down from the liver

It is not clear what the exact function of the omentum is, but it does reach every organ in the abdomen. It is thought by some to act as a "bandage" if the intestine ruptures or there is a local infection. Others contend that it simply maintains the position of the abdominal organs or serves as a storage depot for body fat.

Features of Ovarian Cancer Metastatic to the Omentum

The omentum is affected by the spread of ovarian cancer because it contains a lot of tiny blood vessels. Ovarian cancer cells that have broken away are easily transported and implanted here via the networks of blood vessels, where they can multiply and form new tumors.

Symptoms

The reason that ovarian cancer is frequently diagnosed in the later stages is that there are often few signs or symptoms in the early stages. If the omentum is affected, there may be few, if any, notable symptoms.

Even when symptoms do eventually appear, they are often non-specific and may include:

• Abdominal bloating and swelling
• Quickly feeling full when eating
• Pelvic pain
• Fatigue
• Back pain
• Changes in bowel habits
• A frequent need to urinate
• Unintended weight loss

Diagnosis and Treatment

When ovarian cancer is diagnosed, imaging tests such as a magnetic resonance imaging (MRI) scan or computed tomography (CT) scan are ordered to check for signs of metastasis in the omentum and other organs.

The treatment of metastatic ovarian cancer—also known as stage 4 ovarian cancer—typically involves "debulking" surgery and chemotherapy (and possibly targeted drugs).

Debulking surgery, also known as cytoreductive surgery, is a mainstay of ovarian cancer treatment and aims to remove as much tissue that can harbor cancer cells as possible.

Based on an evaluation by your cancer treatment team, the treatment of metastatic ovarian cancer may involve:

• Chemotherapy before and after surgery (interval debulking surgery)
• Chemotherapy after surgery (debulking surgery)
• Chemotherapy without surgery

The Role of the Omentum in Ovarian Cancer Treatment

The omentum is a critical focus of cancer treatment, in part because it acts as something of a stopgap between the ovaries and the stomach and abdominal organs.

As such, the omentum will be removed in a surgical procedure known as an omentectomy to limit the spread of cancer. Doing so also means there is less cancer to treat—and cancer cells are easier to reach by chemotherapy—once this fatty structure is removed.

This is not to suggest that an omentectomy is an easy operation. It is a tedious and time-consuming surgery that takes great precision as small clusters of cancer cells can be interspersed throughout the fatty tissues.

Moreover, an omentectomy can take many hours to perform and may be limited by a person's inability to withstand extended surgery under general anesthesia.

Ovarian Cancer Doctor Discussion Guide

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Other Conditions Affecting the Omentum

Several other conditions can affect the structure and function of the omentum,

When there is excessive storage of fat in the omentum, people develop an apple-shaped body form known as abdominal obesity. Abdominal fat is one of the risk factors for metabolic syndrome which, in turn, increases the risk of heart disease.

The omentum can also develop abdominal adhesions (in which internal scars cause tissues to stick together) due to abdominal surgery, infections, or inflammatory conditions. This can trigger chronic pain and increase the risk of infertility in females. It can also sometimes cause a bowel obstruction that requires emergency surgery.