What Is Liposarcoma and How Is It Treated?

Liposarcoma is a rare type of cancer that develops in fat cells in the soft tissues of the body. It’s also referred to as a lipomatous tumor or soft tissue sarcoma. There are more than 50 types of soft tissue sarcomas, but liposarcoma is the most common.

It can occur in fat cells anywhere in the body, but is most often found in the:

• arms and legs, especially the thighs
• back of the abdomen (retroperitoneal)
• groin

At first glance, a lipoma can appear to be liposarcoma. They both form in fatty tissue, and they both cause lumps.

But these are two very different conditions. The biggest distinction is that lipoma is noncancerous (benign) and liposarcoma is cancerous (malignant).

Lipoma tumors form just under the skin, usually in the shoulders, neck, trunk, or arms. The mass tends to feel soft or rubbery and moves when you push with your fingers.

Unless lipomas cause an increase in small blood vessels, they’re normally painless and not likely to cause other symptoms. They don’t spread.

Liposarcoma forms deeper within the body, usually in the abdomen or thighs. Symptoms can include pain, swelling, and changes to weight. If untreated, they can spread throughout the body.

There are five main subtypes of liposarcoma. A biopsy can tell which type it is.

• Well-differentiated: This slow-growing liposarcoma is the most common subtype.
• Myxoid: Often found in the limbs, it tends to spread to distant skin, muscle, or bone.
• Dedifferentiated: A slow-growing subtype that typically occurs in the abdomen.
• Round cell: Usually located in the thigh, this subtype involves changes to chromosomes.
• Pleomorphic: This is the least common and the one most likely to spread or recur after treatment.

Early on, liposarcoma doesn’t cause symptoms. There may be no other symptoms other than being able to feel a lump in an area of fatty tissue. As the tumor grows, symptoms can include:

• fever, chills, night sweats
• fatigue
• weight loss or weight gain

Symptoms depend on the location of the tumor. For example, a tumor in the abdomen can cause:

• pain
• swelling
• feeling full even after light meals
• constipation
• trouble breathing
• blood in the stool or vomit

A tumor in the arm or leg can cause:

• weakness in the limb
• pain
• swelling

Liposarcoma begins when genetic changes occur in fat cells, causing them to grow out of control. Exactly what triggers those changes isn’t clear.

In the United States, there are about 2,000 new cases of liposarcoma a year. Anyone can get it, but it’s most likely to affect men between the ages of 50 and 60. It seldom affects children.

Risk factors include:

• prior radiation treatment
• personal or family history of cancer
• damage to the lymph system
• long-term exposure to toxic chemicals such as vinyl chloride

The diagnosis can be made with a biopsy. A sample of tissue will need to be removed from the tumor. If the tumor is hard to reach, imaging tests such as an MRI or CT scan can be used to guide the needle to the tumor.

Imaging tests can also help determine the size and number of tumors. These tests can also tell if nearby organs and tissues have been affected.

The tissue sample will be sent to a pathologist, who will examine it under a microscope. The pathology report will be sent to your doctor. This report will tell your doctor whether the mass is cancerous, as well as details about the type of cancer.

Treatment will depend on a number of factors, such as:

• the size and location of the primary tumor
• whether or not the tumor is interfering with blood vessels or vital structures
• whether the cancer has already spread
• the specific subtype of liposarcoma
• your age and overall health

The main treatment is surgery. The goal of surgery is to remove the entire tumor plus a small margin of healthy tissue. This may not be possible if the tumor has grown into vital structures. If that’s the case, radiation and chemotherapy will likely be used to shrink the tumor prior to surgery.

Radiation is a targeted therapy that uses energy beams to kill cancer cells. It can be used after surgery to destroy any cancer cells that may have been left behind.

Chemotherapy is a systemic treatment involving powerful drugs to kill cancer cells. Following surgery, it can be used to destroy cancer cells that may have broken off from the primary tumor.

After finishing treatment, you’ll need regular monitoring to make sure the liposarcoma hasn’t come back. This will likely include physical exams and imaging tests, like CT scans or MRIs.

Clinical trials may be an option as well. These studies can give you access to newer treatments that aren’t yet available elsewhere. Ask your doctor about clinical trials that may be a good fit for you.

Liposarcoma can be successfully treated. Once you’ve completed treatment, follow-ups should continue for at least 10 years, but perhaps for life. Your prognosis depends on many individual factors, such as the:

• liposarcoma subtype
• tumor size
• stage at diagnosis
• ability to get negative margins in surgery

According to the Liddy Shriver Liposarcoma Initiative, surgery combined with radiation therapy has been shown to prevent recurrence at the surgical site in 85 to 90 percent of cases. The initiative lists the disease-specific survival rates of certain individual subtypes as:

• Well-differentiated: 100 percent at 5 years and 87 percent at 10 years
• Myxoid: 88 percent at 5 years and 76 percent at 10 years
• Pleomorphic: 56 percent at 5 years and 39 percent at 10 years

When it comes to well-differentiated and dedifferentiated subtypes, where the tumors form matters. Tumors that develop in the abdomen can be more difficult to remove completely.

According to the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (SEER), the 5-year relative survival rate for people with soft tissue cancer is 64.9 percent.

SEER divides cancers into stages. These stages are based on where the cancer is located and how far it has spread in the body. Here are the relative 5-year survival rates for soft tissue cancer by stage:

• Localized: 81.2 percent
• Regional: 57.4 percent
• Distant: 15.9 percent
• Unknown: 55 percent

These statistics are based on people who were diagnosed and treated between 2009 and 2015.

Cancer treatment is advancing quickly. It’s possible that the prognosis for someone diagnosed today is different than just a few years ago. Remember, these are general statistics and they may not represent your situation.

Your oncologist can give you a much better idea of your outlook.

Liposarcoma is a fairly rare type of cancer that can often be effectively treated. There are many factors that affect your specific treatment options. Talk to your doctor about the specifics of your liposarcoma to learn more about what you can expect.