Liposarcoma

What is liposarcoma?

Liposarcoma is a rare cancer of connective tissues that resemble fat cells under a microscope. It accounts for up to 18% of all soft tissue sarcomas. Liposarcoma can occur in almost any part of the body, but more than half of liposarcoma cases involve the thigh, and up to a third involve the abdominal cavity.

Liposarcoma tends to affects adults between the ages of 40 and 60. When it does occur in children, it is usually during the teenage years.

There are four types of liposarcoma, each with its own unique characteristics and behaviors.

1. Well-differentiated liposarcoma is the most common subtype and usually starts as a low grade tumor. Low grade tumor cells look much like normal fat cells under the microscope and tend to grow and change slowly.
2. Myxoid liposarcoma is an intermediate to high grade tumor. Its cells look less normal under the microscope and may have a high grade component.
3. Pleomorphic liposarcoma is the rarest subtype and is a high grade tumor with cells that look very different from normal cells.
4. Dedifferentiated liposarcoma occurs when a low grade tumor changes, and the newer cells in the tumor are high grade.

The risk of recurrence and metastasis with liposarcoma increases with higher grade. 

What causes liposarcoma?

Scientists do not yet know the cause of liposarcoma. Although patients sometimes notice a tumor after they experience an injury, liposarcoma is not known to be caused by trauma. It is also not known to develop from benign lipomas, which are harmless lumps of fat.

What are the symptoms of liposarcoma?

Most people with liposarcoma do not feel sick. They might notice a lump (which can be soft or firm to the touch) that is usually painless and slow growing. Unfortunately, tumors in the abdomen can grow to be quite large before they are found.

How is liposarcoma diagnosed?

A physical exam is the first step in the liposarcoma diagnosis process. Lumps that are 5cm or larger and deep-seated, firm and fixed to underlying structures are usually considered suspicious.  Imaging tests are the next step and often include an X-ray and an MRI. An experienced radiologist might suspect the diagnosis based on the results of these tests.

There are two main types of biopsy: a needle and a surgical biopsy. The location, incision and technical aspects of the biopsy can affect a patient’s treatment options and outcome. Therefore, it is essential that the biopsy is planned by a surgeon or radiologist experienced with sarcomas.

The results of the biopsy and imaging studies provide physicians with an idea of the “extent of spread,” or stage, of disease that can be used to create a treatment plan.

How is liposarcoma treated?

Surgery is the treatment for primary liposarcomas that have not yet spread to other organs. In most cases, a surgeon will remove the tumor, along with a wide margin of healthy tissue around the tumor, with the goal of leaving the area free of disease and preventing the tumor from returning. Most tumors of the arms and legs can be successfully removed while sparing the involved limb. Occasionally, in about 5% of cases, an amputation is the best way to completely remove the cancer and restore the patient to a functional life. Complete surgical removal of tumors within the abdomen is difficult, in part because of the difficulty in getting clear margins of normal tissue.

The combination of surgery and radiation therapy has been shown to prevent recurrence at the surgical site in about 85-90% of liposarcoma cases. These results vary depending on the subtype of sarcoma that is involved. Radiation therapy may be used before, during or after surgery to kill tumor cells and reduce the chance of the tumor returning in the same location. Radiation therapy that is given before surgery may be more beneficial, but it can also make it more difficult for surgical wounds to heal.

The role of chemotherapy in the treatment of liposarcoma is not clearly defined, but it may be recommended in certain situations where patients are at high risk of recurrence or already have widespread disease.

Prognosis for patients with liposarcoma

Prognosis statistics are based on the study of groups of liposarcoma patients. These statistics cannot predict the future of an individual patient, but they can be useful in considering the most appropriate treatment and follow-up for a patient.

Liposarcoma prognosis is reported based on disease subtype. Five-year disease specific survival rates (chances of not dying from cancer-related causes) are as follows: 100% in well-differentiated liposarcoma, 88% in myxoid liposarcoma, and 56% in pleomorphic liposarcoma. Ten-year survival rates are 87% in well-differentiated liposarcoma, 76% in myxoid liposarcoma and 39% in pleomorphic liposarcoma. However, the site of disease has a strong effect on prognosis of well-differentiated and de-differentiated liposarcoma. If these liposarcomas arise within the abdomen, complete eradication of the tumor in the long term is less common. This is probably because it is difficult for the surgeon to completely remove tumors in this location. 

How are patients followed after treatment?

Routine follow up will continue throughout the patient’s life. It usually includes a physical examination and imaging studies. An MRI or CT scan of the original tumor location is typical, and a chest x-ray or CT imaging is used to detect metastasis