Undifferentiated Pleomorphic Sarcoma

Undifferentiated pleomorphic sarcoma (UPS) is a rare type of cancer that arises in soft tissue. UPS represents about 10 percent of all adult soft-tissue sarcomas, making it one of the most common subtypes. It frequently develops in the thigh and hip region but can occur in other locations as well as in deeper anatomic regions, such as the retroperitoneum. These tumors have a substantial likelihood of metastasizing.They typically develop in older adult patients and are relatively rare in the pediatric population.

Several specific genetic mutations have been linked to undifferentiated pleomorphic sarcoma. These include genes such as TP53 and RB1, which are important tumor suppressors, as well as ATRX, a regulatory gene thought to manage chromatin remodeling. In some instances, genes may be amplified, while in other cases, certain genes may be deleted or lost. There is no evidence that environmental, social, dietary or other external factors contribute to its development.

Patients will often note a sizable, growing, painless lump. Pain is sometimes reported, but often these lumps are not particularly uncomfortable, prompting some patients to delay seeking medical attention. These tumors can grow rapidly and often reach sizes between five and 15 centimeters in diameter or larger. As they enlarge, the overlying skin can appear taught or stretched. Deeper structures or organs can be compressed, leading to a constellation of symptoms, depending on what is being impacted.

Undifferentiated pleomorphic sarcoma is diagnosed using imaging studies, such as X-rays and MRI. A CT scan of your chest, a PET scan or a PET CT is often also obtained to detect the extent of the disease. Ultimately, a biopsy is required to sample the tumor and review its microscopic appearance.

Treatment for undifferentiated pleomorphic sarcoma generally involves surgery. When the tumor is small and found in just one part of the body, surgery is sometimes enough and no additional treatments are required. 

If the tumor is larger than five centimeters, the combined use of surgery and radiation therapy offers patients better control of their disease, meaning a lower risk of local recurrence. A variety of radiation techniques can be used, and the exact method of delivery is tailored to a patient’s individual circumstances and clinical needs. If the tumor is large or if it has metastasized, treatment will often also include chemotherapy. 

Novel therapies for undifferentiated pleomorphic sarcoma are being explored, often within the context of ongoing clinical trials. These include a wide variety of targeted agents designed to affect one or more specific pathways. The role of immunotherapy is being currently explored.

Following the completion of treatment, patients typically require close monitoring for a period of five years. This includes physical examinations and periodic imaging studies. Many patients continue to follow up even after five years, though at a reduced rate.