Omental metastasis is the spread of cancer to the omentum, a layer of fatty tissue inside the abdomen that covers the intestines and other organs. When cancer cells from a primary tumor, such as in the ovaries or stomach, travel to the omentum, they can form new tumors. This development signifies that the cancer has reached an advanced stage.
The Omentum’s Role in Cancer Spread
The omentum is a large, apron-like fold of tissue that hangs from the stomach. It is an active organ with a rich supply of blood vessels and lymphatic channels, which support its role in immune response and tissue repair. The omentum contains collections of immune cells called milky spots, designed to trap foreign particles in the abdominal cavity.
These features also make the omentum a common site for metastasis. Cancer cells that detach from a primary tumor can be carried through the abdominal fluid. The omentum’s milky spots can inadvertently trap these malignant cells, providing a place for them to lodge and grow.
Its high concentration of fat cells (adipocytes) provides an energy-rich environment, supplying lipids that fuel tumor growth. The omentum also secretes growth factors that promote angiogenesis, the formation of new blood vessels. This process establishes a dedicated blood supply for new tumors, allowing them to expand.
Primary Cancers and Associated Symptoms
Several cancers tend to spread to the omentum due to their location in the abdominal cavity. Ovarian cancer is the most common primary cancer to cause omental metastasis. Cancers of the digestive system, including gastric (stomach), colorectal, and pancreatic cancers, also frequently spread to this area. Other cancers that can lead to omental tumors originate in the endometrium, appendix, or gallbladder.
Symptoms are caused by the physical presence of tumors. A frequent symptom is ascites, the buildup of fluid in the abdomen, which leads to bloating, swelling, and pressure. This occurs when tumors interfere with the normal drainage of abdominal fluid.
Growing tumors can also press on the stomach and intestines, causing a range of symptoms. These include:
- A feeling of fullness after eating a small amount (early satiety)
- Abdominal pain
- Changes in bowel habits, such as constipation or diarrhea
- Nausea and unexplained weight loss
These symptoms can also overlap with those of the primary cancer.
The Diagnostic Process
Diagnosing omental metastasis involves imaging and tissue analysis. The process begins with imaging studies to visualize the abdominal cavity, often prompted by symptoms or as part of staging for a known primary cancer.
Computed tomography (CT) scans can reveal thickening of the omentum, known as an “omental cake,” or the presence of masses. Positron emission tomography (PET) scans use a radioactive tracer to detect areas of high metabolic activity, identifying cancerous spots a CT might miss. An ultrasound may be used to assess for ascites and can sometimes show changes in the omentum.
A definitive diagnosis requires a biopsy to examine a tissue sample for cancer cells. This is often done through laparoscopy, a minimally invasive surgery using a small camera. If ascites is present, a paracentesis may be performed to drain and analyze the fluid for cancer cells.
Current Treatment Approaches
Treatment for omental metastasis aims to control the cancer, relieve symptoms, and improve quality of life. The approach depends on the primary cancer, the extent of spread, and the patient’s health, often combining surgery and chemotherapy.
Surgical Intervention
An omentectomy, the complete removal of the omentum, is a primary surgical procedure. It removes the bulk of the tumor, which can alleviate symptoms and reduce the body’s cancer burden. This is often part of a larger cytoreductive or debulking surgery, which aims to remove as much visible cancer as possible from the abdomen.
Chemotherapy
Chemotherapy can be administered systemically, with drugs traveling through the bloodstream to reach cancer cells throughout the body. For cancers mainly in the abdominal cavity, intraperitoneal chemotherapy may be used. This method delivers drugs directly into the peritoneal cavity, allowing a higher concentration to reach tumors on the omentum.
Specialized and Newer Treatments
Hyperthermic Intraperitoneal Chemotherapy (HIPEC) is an option performed with cytoreductive surgery. During HIPEC, a heated chemotherapy solution is circulated throughout the abdomen to destroy remaining microscopic cancer cells. Depending on the primary cancer’s characteristics, newer treatments like targeted therapy and immunotherapy may also be used.
Impact on Prognosis and Quality of Life
Because omental metastasis indicates an advanced stage of cancer, it affects the overall prognosis. The outlook varies based on the primary cancer type, the extent of the spread, and its response to treatment. While the prognosis can be poor for some cancers, aggressive treatment can lead to better outcomes for others.
Managing symptoms to maintain quality of life is a central goal of treatment. Palliative care focuses on relief from symptoms and stress, which includes managing pain and controlling ascites through regular drainage (paracentesis). Addressing nutritional difficulties is also a component of this care.
Bowel obstructions may occur if tumors block the intestines, sometimes requiring interventions to bypass the blockage. Since nausea and early satiety can make eating difficult, patients may receive dietary counseling. A comprehensive care plan addresses both the cancer and the physical and emotional challenges of the diagnosis.