Mesothelioma is a rare and aggressive cancer that originates in the thin lining of various internal organs, known as the mesothelium. Spindle cell mesothelioma is a particularly aggressive subtype of this cancer, often diagnosed late.
Understanding Spindle Cell Mesothelioma
Spindle cell mesothelioma, also known as sarcomatoid mesothelioma, is distinguished by the elongated, spindle-shaped appearance of its cancerous cells when viewed under a microscope. These cells differ significantly from the more common epithelioid cells, which are cuboidal or polygonal. This distinct cell morphology makes it challenging to differentiate from other sarcomatoid cancers.
This subtype is rare, accounting for approximately 10% to 20% of all mesothelioma diagnoses, with some sources indicating 10-15% of pleural cases and 4% of peritoneal cases. Spindle cell mesothelioma predominantly affects the lining of the lungs, known as the pleura, but can also occur in the peritoneum (lining of the abdomen) and, less commonly, the pericardium (lining of the heart) or tunica vaginalis (lining of the testes). It is known for its aggressive growth and tendency to spread rapidly to distant organs.
Causes and Risk Factors
The primary cause of mesothelioma, including the spindle cell subtype, is exposure to asbestos. Asbestos is a naturally occurring mineral composed of microscopic fibers that, when inhaled or ingested, can become lodged in the mesothelial lining of organs. Over an extended period, often 15 to 60 years after exposure, these trapped fibers can cause irritation, inflammation, and scarring, leading to cellular changes and eventually tumor development.
Different types of asbestos, such as chrysotile and amphibole, have been linked to mesothelioma. Occupational exposure, historically common in industries like construction, shipbuilding, and industrial work, represents the most frequent scenario, accounting for approximately 90% of mesothelioma cases. Environmental exposure, legacy asbestos (from older installations), and secondhand exposure (fibers carried home on clothing) also pose risks. Not everyone exposed develops the disease, with only 8% to 13% of individuals with heavy, prolonged exposure ultimately receiving a diagnosis.
Recognizing Symptoms and Diagnosis
Recognizing the symptoms of spindle cell mesothelioma can be difficult as they often overlap with other forms of mesothelioma and can initially be non-specific. Common symptoms include shortness of breath, persistent chest pain, unexplained weight loss, and abdominal swelling. These symptoms typically emerge decades after asbestos exposure.
The diagnostic process usually begins with imaging tests to detect abnormalities. Initial evaluations may involve X-rays, which can reveal fluid accumulation or calcium deposits. A computed tomography (CT) scan often follows, providing detailed images that can show thickened areas. Magnetic resonance imaging (MRI) and positron emission tomography (PET) scans may also be used to assess disease extent.
A definitive diagnosis relies on a biopsy, which involves removing a tissue sample for microscopic examination. Pathologists perform immunohistochemistry, a specialized staining technique, to identify specific proteins within the cells. This is crucial for distinguishing spindle cell mesothelioma from other cancers with similar spindle-shaped cells, by identifying markers like calretinin, cytokeratin 5/6, and WT1 protein, commonly present in mesothelioma cells.
Treatment Approaches
Treatment for spindle cell mesothelioma is complex and often involves a multidisciplinary approach tailored to the individual patient’s disease stage and overall health. Surgery is a primary option for eligible patients, aiming to remove as much of the tumor as possible. Procedures may include pleurectomy/decortication, which removes the lung lining while sparing the lung, or extrapleural pneumonectomy, a more extensive operation involving the removal of the lung, its lining, part of the diaphragm, and the pericardium. For peritoneal mesothelioma, cytoreductive surgery, or debulking, is performed to remove visible tumors from the abdominal cavity.
Chemotherapy is a cornerstone of treatment, often used before surgery (neoadjuvant) to shrink tumors or after surgery (adjuvant) to eliminate remaining cancer cells. Common chemotherapy regimens typically involve platinum-based drugs like cisplatin combined with pemetrexed. Hyperthermic intraperitoneal chemotherapy (HIPEC), a heated chemotherapy solution delivered directly into the abdomen during surgery, may also be used for peritoneal mesothelioma. Radiation therapy can be applied to destroy microscopic cancer cells left after surgery or to alleviate symptoms like pain and shortness of breath by shrinking tumors. Newer systemic therapies, such as immunotherapy, which helps the body’s immune system recognize and fight cancer cells, including checkpoint inhibitors targeting PD-1, PD-L1, and CTLA-4, have shown promise. Targeted therapies, such as bevacizumab, which inhibit the growth of new blood vessels that feed tumors, are also utilized, sometimes in combination with chemotherapy.
Outlook and Management
The prognosis for spindle cell mesothelioma is less favorable due to its aggressive nature and higher resistance to conventional treatments. Patients often face a shorter life expectancy.
Early diagnosis and access to specialized care at mesothelioma centers are important for improving outcomes. Ongoing research and advancements in treatment continue to offer new possibilities. Palliative care and supportive measures play a significant role in managing symptoms, alleviating pain, and improving the overall quality of life for patients throughout their disease journey, addressing both physical and psychological needs.