NORD gratefully acknowledges Preeti Kodavanti, MD candidate at Georgetown University School of Medicine, and Burton Eisenberg, MD, Grace E. Hoag Executive Medical Director Endowed Chair, Hoag Family Cancer Institute, Professor of Surgery USC/Norris Cancer Center, for the preparation of this report.
Liposarcoma is a rare tumor derived from fat tissue that occurs in the “soft tissues” of the body (soft tissue sarcoma). It is classified as a cancer (malignant) because of its potential to recur locally and spread to other areas of the body. The severity of disease depends on the subtype of the liposarcoma and the presenting stage of the primary tumor. It can arise in various locations throughout the body, although it is most frequently found in the extremities particularly in the thigh. It can also grow in the back of the abdomen in an area called the “retroperitoneum” where, because of the vast amount of space, can effectively hide a tumor of substantial size and weight. Some individuals with liposarcoma may not have symptoms in the early stages, but as the tumor grows and advances to later stages, it can potentially compress other tissues and cause pain. The specific genetic cause of liposarcoma has yet to be identified, though studies have proposed that it starts in fat cells that have lost their ability to mature or have unregulated growth. It has been found to be more common in middle-aged males from 50 – 65 years of age compared to females and is very rare in children. The mainstay of treatment is surgery or chemotherapy/radiation depending on the staging of the tumor at presentation.
As previously mentioned, most patients who are diagnosed with liposarcoma do not have any early symptoms and it can go unnoticed during the initial stages of the disease until the tumor has grown to a large enough size to compress neighboring tissues and cause pain or decreased function. It can sometimes be noticed as a deep-seated mass to touch. Liposarcoma, as with all other cancers, can present with non-specific symptoms such as fevers, chills, fatigue, night sweats and weight loss. If the tumor is retroperitoneal in location, it can present with specific symptoms in the abdomen, including abdominal or flank pain, swelling, and constipation or the sensation of feeling full sooner than expected after eating.
There are five subtypes of liposarcoma: well differentiated, dedifferentiated, myxoid, round cell and pleomorphic. The well differentiated type is less aggressive and tends to be a large painless mass found in deeper tissues and in the retroperitoneum. Myxoid, round cell and pleomorphic types tend to be in the arms and legs, whereas dedifferentiated tends to be in the retroperitoneum and often associated with the well differentiated variety. Specifically, pleomorphic liposarcoma is the least common subtype with a high rate of recurrence and poor outcomes.
The specific cause of liposarcoma is still unknown. Clinically, it can be first noticed particularly in the extremity in an area of recent trauma where the patient may find a mass, however the cause and effect are quite likely purely coincidental. Liposarcoma generally is attributed to a change in some of the genes that are normally present in fat cells. A series of abnormalities in these genes (mutations or DNA alterations) can lead to malignant changes characterized by uncontrollable growth.
Liposarcoma is a soft tissue sarcoma, affecting approximately 2000 individuals each year in the United States. It affects men more than women, and more specifically middle-aged men ranging from 50 – 65 years of age. Children are rarely diagnosed, but when liposarcoma does occur in children, it is usually during adolescence. There is no specific ethnicity in which liposarcoma is more common. Certain risk factors have been shown to predispose individuals to developing soft tissue sarcomas, such as liposarcoma, including: prior radiation, familial cancer syndromes, damage to the lymph system, and long term exposure to certain toxic chemicals such as vinyl chloride, a chemical used to make plastic.
The most critical step in the diagnosis of liposarcoma involves taking a biopsy of the mass of concern. A biopsy is when tissue is retrieved from the tumor in order to be evaluated under the microscope to assess whether or not the tissue has tumor-specific features. Since many of these tumors are deeply embedded into the body, imaging such as ultrasound can be used to guide where the needle is relative to the mass and ensure that the tissue sample is retrieved specifically from that mass.
Liposarcoma can also be diagnosed by imaging the body either by computed tomography (CT) or magnetic resonance imaging (MRI). CT uses multiple X-ray measurements to create an image of the body and it is important in assessing the location of a mass and its relationship to surrounding tissues. MRI is another way to image liposarcoma and it can show characteristics of the mass itself which might be helpful in diagnostic differences between benign and malignant soft tissue masses.
Therapy to treat liposarcoma largely depends on the type, size and location of the tumor. Surgery is a favored option compared to others, but there are certain cases where it would be riskier to attempt to remove the tumor surgically. For example, this can occur if it is located in the retroperitoneum where it is deeply embedded and involves multiple organs. Another example would be if the tumor were adjacent to vital structures, such as major blood vessels, where removing the tumor itself could pose a significant risk. If a tumor spreads in such a way that the mass cannot be completely removed with surgery, chemotherapy or radiation therapy can be considered to kill the rest of the tumor and reduce the risk of the cancer reoccurrence. In certain circumstances, chemotherapy and/or radiation therapy prior to surgery can be considered to shrink the tumor to a size where it can be successfully surgically removed.
The FDA has approved new therapeutic options to treat tumors that are either wide spread or not amendable to surgical removal. Several new chemotherapeutic agents have had some success in liposarcoma management. Erybulin mesylate (Halaven) is administered by injection specifically targets a critical step in cell division that prevents cells from dividing and ultimately kills off tumor cells. Trabectedin (Yondelis) works in a similar manner by interfering with the gene repair mechanism of tumor cells. After treatment, routine follow up will continue on a regular basis with physical exams and imaging studies, such as an MRI or CT to assess for presence of new masses.
Immunotherapy utilizes the body’s natural immune system to target cancer cells and this new innovative technique has been focusing on treating cancers, including liposarcoma. Specifically, immunotherapy drugs such as checkpoint inhibitors and cellular T-cell therapy have either been studied in treating sarcomas or are soon to go into clinical trials. Checkpoint inhibitors, such as ipilimumab (Yervoy), nivolumab (Opdivo) and pembrolizumab (Keytruda), block specific receptors on cells and release a natural brake on immune cells, allowing for them to activate and target cancer-specific cells. T cell therapy involves removing normal T cells from the human body and modifying these cells so that they can recognize and attack cancer cells based on the specific cell markers expressed on their surface.
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Liposarcoma. Genetic and Rare Diseases Information Center. Last updated: 6/23/2016. https://rarediseases.info.nih.gov/diseases/6913/liposarcoma . Accessed April 30, 2018.
Liposarcoma. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/liposarcoma/diagnosis-treatment/drc-20352635 Published November 21, 2017. Accessed April 30, 2018.
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