Synovial carcinoma is a rare and aggressive form of cancer that originates in the body’s soft tissues. It is classified as a soft tissue sarcoma, a group of cancers that develop in the connective tissues supporting and surrounding organs and other body structures. This malignancy often forms near large joints, but its aggressive nature means it can also appear in various other locations.
Understanding Synovial Carcinoma
Synovial carcinoma is a distinct type of soft tissue sarcoma, despite its name suggesting an origin from synovial tissue, which lines joints. This is a misnomer, as the cancer actually arises from primitive mesenchymal cells, not from the joint lining itself. It is a rare disease, with an incidence of about 1 to 2 cases per million people annually.
This cancer is most commonly found in the extremities, such as the arms or legs, often in proximity to major joints like the knee, ankle, shoulder, or wrist. However, it can also develop in other areas, including the head and neck, trunk, or even internal organs. It is aggressive due to its tendency to invade surrounding tissues and spread to distant parts of the body, most frequently the lungs.
Recognizing the Symptoms
Synovial carcinoma often presents as a noticeable lump or mass in the affected area. This mass may or may not cause pain, especially in its early stages. The size of the lump can vary, and it might grow slowly over time, sometimes remaining unnoticed for an extended period before diagnosis. If the tumor is located near a joint, it can lead to swelling or a limited range of motion in that joint. Should the mass press on nerves, individuals may experience pain, numbness, or tingling sensations in the area.
Diagnosis Methods
Diagnosis typically begins with imaging studies to visualize the tumor and assess its characteristics. X-rays, CT scans, and MRI scans are commonly used to determine the tumor’s size, exact location, and its relationship to surrounding tissues. MRI provides detailed soft tissue images.
A definitive diagnosis requires a biopsy, where a small tissue sample is taken from the tumor. This sample is then examined by a pathologist under a microscope to identify the cancer cells. Pathological examination can involve different biopsy types, such as incisional, excisional, or core needle biopsies.
A key diagnostic feature for synovial carcinoma is the presence of a specific genetic abnormality: the SYT-SSX fusion gene, resulting from a translocation between chromosome X and chromosome 18. Molecular testing for this gene confirms the diagnosis and distinguishes synovial carcinoma from other soft tissue tumors, as it is present in over 95% of cases.
Treatment Approaches
Surgical Treatment
The primary treatment for localized synovial carcinoma is surgical resection, aiming for complete removal of the tumor along with a margin of healthy tissue. Achieving clear margins reduces the risk of local recurrence. The feasibility and extent of surgery depend on the tumor’s size, location, and whether it has invaded nearby structures.
Radiation Therapy
Radiation therapy is often used in conjunction with surgery, either before (neoadjuvant) or after (adjuvant) the procedure. Pre-operative radiation can shrink the tumor, potentially making it easier to remove and increasing the chances of clear margins. Post-operative radiation helps eliminate any remaining cancer cells in the tumor bed, further reducing the risk of the cancer returning in the same area.
Chemotherapy
Chemotherapy plays a role, particularly for advanced or metastatic synovial carcinoma, or when there is a high risk of the cancer spreading. Chemotherapy drugs, such as doxorubicin and ifosfamide, are commonly employed to target and destroy cancer cells throughout the body. The goal of chemotherapy is to control disease progression, reduce tumor size, and improve survival rates in cases where the cancer has spread beyond the primary site.
Targeted and Immunotherapies
Emerging treatment strategies for synovial carcinoma include targeted therapies and immunotherapies. Targeted therapies focus on specific molecular pathways involved in the cancer’s growth, such as EZH2 inhibitors like tazemetostat. Immunotherapy aims to boost the body’s own immune system to recognize and fight cancer cells. These newer approaches offer additional options, especially for patients with advanced disease who may not respond to conventional treatments.
Prognosis and Follow-up Care
Prognosis Factors
The prognosis for individuals with synovial carcinoma is influenced by several factors. These include the tumor’s size at diagnosis, its specific location, whether it has spread to lymph nodes or distant sites (stage of disease), and the patient’s overall health. Tumors that are smaller and can be completely removed with clear surgical margins generally have a more favorable outlook. The presence of metastases, particularly to the lungs, significantly impacts the prognosis.
Follow-up Care
Following initial treatment, ongoing surveillance and follow-up care are important. This typically involves regular physical examinations and imaging scans, such as MRI or CT scans, to monitor for any signs of recurrence or the development of new metastases. The frequency of follow-up appointments and scans is tailored to the individual’s risk factors and disease stage. Long-term management focuses on early detection for timely intervention.