Rhabdomyosarcoma (RMS) is a rare cancer originating in soft tissues, specifically skeletal muscle cells. While common in children, RMS is uncommon in adults, accounting for less than one percent of adult soft tissue sarcomas annually. This cancer develops from primitive mesenchymal cells that would normally differentiate into skeletal muscle tissue.
Subtypes and Locations in Adults
Rhabdomyosarcoma is categorized into several histological subtypes: embryonal, alveolar, pleomorphic, and spindle cell/sclerosing. Pleomorphic rhabdomyosarcoma is the subtype most frequently identified in adults, often appearing in individuals in their 50s and 60s. Embryonal and alveolar subtypes are more commonly diagnosed in children and adolescents, though they can also affect young adults.
RMS tumors in adults are often found in the extremities, such as the arms and legs, and can grow rapidly in these areas. Other common sites include the trunk, encompassing the chest and abdomen, and the head and neck region. The genitourinary system, including the bladder, prostate, and areas around the testicles or vagina, also represents a common site for adult RMS.
Symptoms and Diagnostic Process
Symptoms of rhabdomyosarcoma vary depending on the tumor’s location. A common initial sign is a growing, often painless, lump or swelling in an arm or leg. If the tumor is in the head or neck, individuals might experience nasal congestion, changes in vision, or difficulty swallowing. Tumors in the genitourinary tract can lead to symptoms such as blood in the urine, difficulty urinating, or a noticeable lump.
The diagnostic process typically begins with a physical examination. Imaging tests follow to provide detailed views of the tumor’s size, location, and spread. These imaging modalities include computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET) scans. A definitive diagnosis is established through a biopsy, which involves removing a small tissue sample from the tumor for microscopic examination by a specialized pathologist.
Adult-Specific Treatment Protocols
Treatment for rhabdomyosarcoma in adults typically involves a multimodal approach combining surgery, radiation therapy, and chemotherapy. Surgery aims to remove the tumor completely, along with a margin of healthy tissue. If the tumor is too large or located in a challenging area, chemotherapy or radiation therapy may be administered first to shrink it, making surgical removal more achievable.
Radiation therapy uses high-energy beams to target and destroy remaining cancer cells, often delivered after surgery or in conjunction with chemotherapy. Chemotherapy involves powerful drugs to kill cancer cells throughout the body, addressing the primary tumor and any potential microscopic spread. Common chemotherapy agents used in adult RMS regimens include doxorubicin, ifosfamide, and vincristine.
Adult RMS treatment protocols often differ from pediatric regimens, as adult RMS can be less responsive to standard chemotherapy. This necessitates individualized plans, often involving adjustments to medications or dosages to suit the patient’s response and tolerance. For many adults with this rare cancer, participation in clinical trials offers access to novel therapies and contributes to advancing knowledge about the disease.
Prognosis and Outlook for Adults
The prognosis for adults diagnosed with rhabdomyosarcoma is generally more challenging compared to children. Several factors influence the outlook. The specific subtype of the tumor plays a role, as pleomorphic rhabdomyosarcoma, common in adults, often has a different outlook than other types.
The stage of the cancer at diagnosis, particularly if it has spread to distant sites like lymph nodes, lungs, or bone marrow, significantly impacts prognosis. The tumor’s location and size also factor into the outlook. Response to treatment is another important determinant; how well the cancer shrinks or disappears following therapy directly influences the outcome. Long-term follow-up care is routinely recommended to monitor for any signs of recurrence.