What is Mesothelioma: Causes Symptoms Diagnosis Treatment. Mesothelioma is a rare and very aggressive tumor that affects the pleura, and its main cause is exposure to asbestos, a mineral used in the building whose use was banned four decades ago.
Mesothelioma is a tumor that is derived from the mesothelial cells of the pleura, peritoneum, pericardium and tunica albuginea of the testis. The mesothelium is a membrane that covers all our cavities internally.
The pleural location is the most frequent (80%), affecting the pleura diffusely. The pleura is the membrane that covers the rib cage and the surface of the lungs.
It is a rare tumor. It occurs between the 5th and 7th decade of life due to previous occupational exposure to asbestos or asbestos (a mineral) in youth. The incidence is highest in Australia, Belgium and Great Britain (with more than 20 cases per million inhabitants); In Spain, the incidence is less than 22 cases per million, and mesothelioma accounts for 0.3% of cancer deaths. The incidence is higher in males than in females.
The average survival of those affected by malignant mesothelioma is between six and 18 months.
What is Mesothelioma: Causes Symptoms
Causes of Mesothelioma
Asbestos – the commercial name for a mineral consisting of silica, magnesium, lime and ferrous oxide – is the main cause of mesothelioma, and its carcinogenic capacity has been demonstrated in animals. In humans, it has been proven that the risk is proportional to exposure to it, with miners and workers in the naval industry, construction, textiles, and plumbers being the most at risk groups. In fact, it is estimated that up to 10% of workers at risk develop mesothelioma, and 80% of cases of mesothelioma have a history of exposure to this mineral, whose use in construction began to be limited for decades and has been banned In many developed countries (In Spain in 2001), but still present in many of the buildings that surround us. Currently,
The latency period (time between exposure and onset of disease) can be between 14 and 75 years, and other factors that may influence exposure time, intensity and environmental exposure, and there are even cases of familial mesothelioma.
Other causes of mesothelioma include ionizing radiation (increased incidence in patients previously treated with radiotherapy) or SV40 virus, present in 60-86% of mesothelioma samples (although conclusive results can not be drawn from the studies).
Symptoms of Mesothelioma
The initial symptoms of mesothelioma usually appear months before the diagnosis in the form of thoracic pain (not pleuritic, like a puncture, but deaf and poorly located), as well as dyspnea(sensation of respiratory difficulty) variable in relation to the amount of pleural effusion.
A dry cough, fever and night sweats, asthenia (tiredness) and weight loss may also occur. It occurs most unilaterally (95%), and especially in the area of the right hemithorax (60%), probably in relation to its greater volume.
Progression of the disease leads to respiratory failure , and invasion of neighboring structures can lead to dysphagia (difficulty swallowing), dysphonia, brachial plexopathy (involvement of the nerve plexus), or superior vena cava syndrome (when there is compression of this symptom such as dyspnea, facial and arm swelling, cough, chest pain, dysphagia, cyanosis, congestion, headache, and dizziness).
Mesothelioma may also be accompanied by symptoms derived from paraneoplastic syndromes (these are various groups of symptoms that cancer patients suffer, and can not be explained by local tumor invasion or metastasis, but are associated with the release of Biologically active substances by the tumor, which exerts their effects at a distance. In fact, they may be the first sign to warn of the presence of a tumor).
Diagnosis and Staging of Mesothelioma
As the symptoms of this tumor are very nonspecific, the findings of suspected mesothelioma appear with radiology after a history of asbestos exposure. The different radiological tests: Ctor MRI is useful for the extension study or to determine the resectability (operability) or not of the lesion. The PET is superior to CT setting distant disease, but it has its limitations in the locoregional staging.
The collection of a sample for the pathological diagnosis of mesothelioma can be done by thoracocentesis (obtaining the pleural fluid) for a subsequent cytological study, but the profitability of this test is not greater than 33%. The pleural biopsy for obtaining a cylinder of tissue can be done blindly (yield 50%), or open by VATS (VATS), or by thoracotomy, reaching up to 95% return; In addition, reports the extent of the disease to the diaphragm, pericardium, thoracic wall and lymph nodes. This biopsy carries a risk of dissemination by the chest wall in up to 10% of patients.
For mesothelioma staging, the TNM system is used in its 2002 update.
There are many prognostic factors influencing survival (in advanced stages) such as: general patient status, chest pain, dyspnoea, thrombocytosis (platelets> 400000), weight loss, elevated LDH (> 500 UI / l), pleural involvement (compared to pericardium or peritoneum), anemia, leukocytosis, age greater than 75 years, and so on.
Treatment of mesothelioma
The treatment of mesothelioma depends on the stage where the disease is found, and it can be said that there are no standard treatments because of the scarce incidence thereof. The following therapies are currently used:
The surgery with curative intent is, in theory, the best choice for the treatment of mesothelioma, however, complete resection (with large and negative margins) is rarely achieved. Less than 25% of the patients remain alive at 5 years.
We have the following options:
- Extrapleural pneumonectomy: resection of the parietal and visceral pleura together with the lung infiltrated by the tumor, mediastinal lymph nodes, diaphragm, and pericardium. All this is rebuilt with meshes. It is a very complicated technique that is not done in all centers and has high perioperative morbimortality (in highly selected cases and expert hands it is 4%). It has an average survival between 9 and 19 months, and a two-year survival between 9 and 37%.
- Pleurectomy (decortication) : consists of resection of the parietal pleura, including the portion of the mediastinum, pericardium, and diaphragm and part of the visceral pleura. This technique is less aggressive than the previous one and, above all, more functional for the patient; The mortality of the intervention oscillates between 1.5% and 5%, what happens is that with this technique in 80% of the cases a viable tumor remains. This technique does not lengthen survival, but it better controls relapsing pleural effusions, more effectively than talc pleurodesis (attaching the visceral pleura to the parietal by introducing talcum between the two pleural “sheets”). The median survival is between 9 and 20 months
- Videothoracoscopy (VATS) and pleurodesis: the symptomatic treatment of choice is considered.
Although mesothelioma is a radiosensitive tumor, indications for radiotherapy are limited because of proximity to the heart, esophagus, liver, and spinal cord (more radiosensitive structures).
Can be used in
- Prophylactic radiotherapy at the site of biopsy or puncture, to prevent tumor spread.
- Palliative radiation therapy relieves pain in 50% of patients, without influencing survival.
- Adjuvant (complementary) radiotherapy with or without chemotherapy after surgery (although there are no studies showing benefit).
Approximately 85-90% of the patient’s present mesotheliomas as an unresectable disease (locally advanced or metastatic), so the intention of the treatment will be palliative. We have already seen this scenario for surgery and for radiotherapy.
The chemotherapy obtained between 10 and 20% response in monotherapy. The agents used are platinum (cis or carboplatin), anthracyclines (adriamycin) and antimetabolites (pemetrexed). In polychemotherapy schemes, the responses are higher (up to 48%). The most active regimen is cisplatin-pemetrexed, so it can be considered the standard treatment for the unresectable disease. Another drug to be considered in combination with platinum (even with oxaliplatin) is raltitrexed.
The new anti-Indian agents (antiangiogenic or inhibitors tyrosine kinase) have not demonstrated, by now, their utility.