More than one-third of women with ovarian cancer develop ascites (pronounced uh٠SAI٠teez), an accumulation of fluid in the abdomen. Ascites, which also occurs in people with liver disease and occasionally with other conditions, can lead to bloating, pain, discomfort, nausea, as well as trouble moving around, eating, or breathing. While this fluid buildup often comes back repeatedly in women with advanced ovarian cancer, physicians can treat ascites in a few ways.
Ascites is the medical term for extra fluid inside the abdomen, in the space between organs. When ascites is associated with cancer, and cancer cells are found inside this extra fluid, it is referred to as malignant ascites. But people with other conditions, including liver failure, cirrhosis, heart failure and pancreatitis, can also accumulate abdominal fluid—called non-malignant ascites.
In some people with ovarian cancer, ascites might occur because a tumor has spread to the lining, or peritoneum, of abdominal organs. The peritoneum helps control the flow of liquids and nutrients in and out of organs, and when it has been compromised by cancer cells, fluid may leak out of these organs.
In other cases, ascites develops when a person’s cancer has damaged the liver; the blood vessels leading to the liver can then become backed up and leak fluid. Or, ascites may occur when tumor cells are blocking the lymph system which normally drains fluid from the abdomen. This is the same reason that lymphedema—an accumulation of fluid in soft tissues—happens in the arms or legs of some people with cancer.
People with ascites often feel bloated, swollen, tight or full in their abdomen. Other symptoms of ascites include:
- Shortness of breath
- Abdominal tenderness and pain
- Loss of appetite or indigestion
- Impaired movement
- Back pain
- Needing to urinate often
When malignant ascites is diagnosed in patients with early-stage ovarian cancer, or is not causing severe symptoms, physicians generally treat it indirectly—by treating the underlying cancer with chemotherapy. As the ovarian tumor shrinks, the ascites may go away itself.
In some cases of malignant ascites, when the fluid accumulation is associated with liver damage due to cancer spread, patients can be prescribed a diuretic, or water pill, that helps move fluid from the body to the urine.
In women with more advanced disease, or in those with more severe symptoms of ascites, doctors turn to a procedure called a paracentesis. In a paracentesis, a thin needle is used to drain fluid out of the abdomen. This can immediately ease symptoms, but ascites often returns in days to weeks.
If ascites keeps recurring, some women with ovarian cancer opt to get a flexible tube inserted into the space where the fluid is. This lets patients or caregivers drain the fluid more often, and they can do this at home.
Studies have established that ovarian cancer patients with ascites tend to have more severe disease and worse outcomes. Ascites is associated with the spread and recurrence of ovarian cancer as well as the development of resistance to treatment. When ascites develops during, or immediately after, chemotherapy treatment, physicians often consider it a marker that the chemotherapy is not effective.
Those associations are partly because ascites is often a sign that a tumor has spread throughout the abdomen, so women with ascites likely already have advanced ovarian cancer. More than 90% of women with stage III and IV ovarian cancer have ascites.
In addition to being a marker for more advanced cancer, researchers think that ascites can also worsen these advanced cancers, as the mixture of cancer cells, molecules and nutrients contained in ascites fluid has been shown to encourage tumor growth and spread. Moreover, ascites is linked to a worse quality of life—the pain and effect on eating and breathing can contribute to further complications for women.
To better understand how cancers grow and spread, researchers collect repeated samples from tumors and study how cells within those tumors change over time. However, women with ovarian cancer rarely have multiple surgeries, so researchers don’t often have the opportunity to collect ovarian cancer cells from different timepoints in one patient’s disease.
Ascites fluid, easily collected through a thin needle, might change that. Scientists have discovered that the cancer cells found floating in ascites can be used to track the progression of ovarian cancer and identify which women with ovarian cancer are most likely to respond to which treatments. As research on ascites continues, it might eventually lead to new ways to diagnose, monitor or treat ovarian cancer.