Ascites is the buildup of fluid within the abdominal (peritoneal) cavity. This fluid accumulation can arise from various health issues, including certain types of cancer. When cancer is the underlying cause, it is known as malignant ascites and can significantly impact a person’s comfort and health.
Understanding Ascites
Ascites involves an excess accumulation of fluid in the peritoneal cavity. When fluid accumulates, it can lead to noticeable symptoms such as abdominal swelling, a feeling of fullness, and discomfort. Other common symptoms include rapid weight gain, nausea, loss of appetite, and shortness of breath due to pressure on the diaphragm. While many cases of ascites are caused by non-cancerous conditions like liver cirrhosis, its presence in individuals with cancer often indicates advanced disease. Diagnosis typically involves a physical examination, imaging tests like ultrasound or CT scans, and analysis of the fluid itself, which can confirm the presence of cancer cells.
Primary Cancers Linked to Ascites
Several types of cancer are frequently associated with ascites, particularly as the disease progresses. Ovarian cancer is a common cause, as it often spreads to the peritoneal lining of the abdomen. Gastrointestinal cancers, including those of the stomach, colon, and pancreas, are also significant contributors to ascites, often spreading to the peritoneum. Pancreatic cancer, specifically, can lead to ascites when it has metastasized.
Liver cancer, or cancers that have spread to the liver, can also result in ascites. Breast and lung cancers, although originating outside the abdomen, can cause ascites if they metastasize to the peritoneal cavity. Lymphoma, a cancer of the lymphatic system, may lead to ascites. Peritoneal mesothelioma, a rare cancer affecting the abdominal lining, also commonly presents with ascites.
Mechanisms of Cancer-Related Ascites
Cancer can cause fluid accumulation in the abdomen through several distinct physiological mechanisms. One common way is through peritoneal carcinomatosis, where cancer cells spread directly onto the peritoneum, the membrane lining the abdominal cavity. These invading cells irritate the peritoneum, causing inflammation and prompting it to produce excessive fluid.
Another mechanism involves the obstruction of lymphatic vessels. The lymphatic system normally drains fluid from the abdominal cavity, but cancer cells can block these vessels, preventing proper fluid removal. This blockage leads to a buildup of fluid that cannot be reabsorbed effectively.
Liver metastasis and subsequent portal hypertension can also contribute to ascites. When cancer spreads to the liver, it can impair the liver’s function and increase pressure within the portal vein system. This elevated pressure can force fluid to leak out of blood vessels and accumulate in the abdominal cavity. Furthermore, cancer cells can release substances that increase the permeability of blood vessels. Factors such as Vascular Endothelial Growth Factor (VEGF) are known to make blood vessel walls more porous, allowing fluid and proteins to leak into the peritoneal space. This increased vascular permeability, combined with inflammatory responses triggered by the tumor, contributes significantly to the formation of ascites.