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Mesothelioma Without Exposure To Asbestos
It is a known fact that asbestos is one of the significant contributors to mesothelioma. Most people wonder if there are other things aside from asbestos that cause mesothelioma. The answer is that other factors could cause mesothelioma or increase the risk of it. This article seeks to shine more light on these factors, but first, let's have a look at what mesothelioma is and its types.
What Is Mesothelioma?
Mesothelioma is a cancerous disease of the outer tissue covering the lungs (pleura), heart, stomach, and other body organs. Mesothelioma can be malignant or non-malignant, and its cause is mainly linked to asbestos exposure. Like most cancer diseases, mesothelioma could result from genetic and environmental exposure to toxic substances or chemicals.
Types Of Mesothelioma
Mesothelioma is categorised into two groups, namely:
• Cancerous or malignant mesothelioma
• Benign or non-cancerous mesothelioma
Cancerous/Malignant Mesothelioma
Here, the mesothelioma tumours are cancerous and life-threatening. Malignant mesothelioma is characterised by tumours that grow from the pleura and rapidly spread towards the other part of the lungs and the chest cavity. This category of mesothelioma is primarily incurable; however, it can be managed by adjusting to the patient's lifestyle and suitable medications.
Malignant mesotheliomas are divided into three types:
• Pleural mesothelioma
• Pericardial mesothelioma
• Peritoneal mesothelioma
Pleural mesothelioma
This type of malignant mesothelioma affects the tissues lining or covering the lungs. Approximately 70 to 80 per cent of reported mesothelioma cases are mostly pleural mesothelioma. It is the most common form of mesothelioma associated with long-term asbestos exposure.
The latency period for pleural mesothelioma is about 30 to 50 years after asbestos exposure, with the latency period differing in patients. Pleural mesothelioma is further divided into three depending on the tissues involved:
• Epithelial pleural mesothelioma
• Sarcomatoid pleural mesothelioma
• Biphasic pleural mesothelioma
Due to its long latency period, pleural mesothelioma is not easily diagnosed. In addition, pleural mesothelioma can reduce a patient's life expectancy. However, early diagnosis and detection can help extend life expectancy in patients suffering from pleural mesothelioma.
• Fever, severe fatigue, abrupt weight loss, and oedema (excessive fluid collection)
• Difficulty in breathing due to fluid build-up in the lungs
• Shortness of breath
• Difficulty in swallowing
• Swelling in the face and arms
• Cough (might be persistent)
Being on the lookout for these symptoms could help in the early detection of pleural mesothelioma.
Pericardial mesothelioma
Pericardial mesothelioma mainly affects the tissue covering the heart. The cancerous tumour in this type of mesothelioma grows in the pericardium (the tissue or membrane surrounding the heart). This is explicitly located between the two membranes of the pericardium that encapsulate the heart.
The tumour growth causes these membranes to become thicker, resulting in pain in the chest region. It is the rarest type of mesothelioma and accounts for only around one to two per cent of diagnosed cases. Pericardial mesothelioma occurs mainly as a direct result of asbestos exposure or through the extension of other asbestos-related cancers.
Generally, all forms of mesothelioma are difficult to diagnose, but pericardial mesothelioma is even more challenging to diagnose. Most cases are detected through an autopsy after the patient's death. However, an X-ray or CT scan could also diagnose pericardial mesothelioma. These scans detect pericardial effusions (fluid build-up around the heart) and also reveal any tumour growth around the heart.
Additional pericardial diagnosis methods
Pericardial mesothelioma could also be diagnosed with an echocardiogram. This involves using sound waves to detect problems with the heart. With an echocardiogram, the physician can listen to a patient's heartbeat and ensure that the heart is pumping enough blood. Tissue and fluid biopsy are another way in which pericardial mesothelioma is diagnosed.
A sample of the heart tissue is taken and studied under a microscope for visible signs of tumour growth with tissue biopsies. It is the most critical step in diagnosing all forms of mesothelioma. On the other hand, with fluid biopsies, a fluid sample is taken from the affected tissues and examined for cancer in the cells. Tissue biopsies are more accurate and precise than fluid biopsies.
Symptoms of pericardial mesothelioma
The symptoms of pericardial mesothelioma include the following:
• Pericardial effusion
• Difficulty in breathing (dyspnea)
• Inflammation in the pericardium (constrictive pericarditis)
• Sweating mostly at night
• Pain in the chest region
• Weight loss due to reduced or complete lack of appetite
• Compression of the heart, which results from fluid build-up. It is also called cardiac tamponade.
These symptoms could take decades to appear and could quickly become severe. This will have huge effects on the patient's body very fast. It could even reduce or impair the proper functioning of the heart or even lead to heart failure. Your general practitioner (GP) can treat pericardial mesothelioma with chemotherapy and surgery like pericardiectomy.
A pericardiectomy procedure involves the surgical removal of the cancerous tumour. This is followed by chemotherapy, cisplatin, and pemetrexed to stop or slow down tumour growth in the pericardium. These treatment options are more effective at the early stage of pericardial mesothelioma. In the late stages of the disease, these treatment options can only help reduce pain and extend the patient's life.
Peritoneal mesothelioma
Peritoneal mesothelioma typically affects the tissue surrounding the abdominal organs (known as the peritoneum) and pelvic walls. The peritoneum comprises two membranes, namely:
• The visceral peritoneum. This is the inner membrane lining the ovaries, liver, and bowel surface.
• The parietal peritoneum, which is the outer membrane that lines the pelvic walls and abdomen.
Peritoneal mesothelioma could affect either one or both of these membranes at the same time. Between these two membranes is the cavity housing a thin film of fluid, which enables the two membranes to slide or glide over one another during body movement. In the presence of peritoneal mesothelioma, an extra fluid from the tumour growth would collect alongside the film and cause swelling or bloating in the membrane cavity. The swelling or bloating could cause unbearable pain.
Less than around 10% of mesothelioma cases are peritoneal. Asbestos exposure is a significant cause of peritoneal mesothelioma and the latency period is about 30-50 years after asbestos exposure. Early detection of peritoneal mesothelioma helps to extend the life expectancy of patients.
The symptoms of peritoneal mesothelioma include nausea or vomiting, pain in the abdomen ranging from acute to severe, difficulty in breathing, reduced or total loss of appetite, anaemia, swelling of the abdomen, and bowel obstruction. Just like pericardial mesothelioma, your GP can treat peritoneal mesothelioma with surgery and hyperthermic intraperitoneal chemotherapy.
Usually, surgery is undertaken to get rid of the cancerous tumour. Afterwards, warm chemotherapy drugs are inserted into the thoracic cavity. These warm chemotherapy drugs kill off cancerous cells not entirely removed during the surgery.
Benign/Non-Cancerous Mesothelioma
This category of mesothelioma involves a tumour growth that is non-cancerous, non-metastatic and does not spread to other parts of the body. These non-cancerous tumours are not caused by asbestos exposure and could occur at any age. Benign mesothelioma tumours usually stem from the rapid growth and division of healthy cells.
When these healthy cells overgrow, they form solid lumps, which result in tumour growth. They are equally rare, just like other forms of mesothelioma but can easily be removed by surgery. Compared to malignant mesothelioma, benign mesothelioma is not life-threatening as it is entirely curable and can be treated with complete recovery.
However, there have been reported cases of the tumour growing back after treatment. Unfortunately, these recurring benign tumours could become malignant or cancerous in the long run. Unlike the malignant tumours of the cancerous types of mesothelioma, benign tumours do not spread or invade the surrounding tissues, so they are considered less severe.
The tumours of benign mesothelioma, although not life-threatening, could cause discomfort and health complications. The symptoms of benign mesothelioma are pretty similar to those of malignant mesothelioma. However, some signs of malignant mesothelioma, like weight loss, fever, and sweating at night, are not seen or experienced in cases of benign mesothelioma.
Non-cancerous mesothelioma symptoms
The symptoms of non-cancerous mesothelioma include:
• Persistent or chronic coughs
• Pain in the chest
• Shortness of breath and difficulty in breathing
Benign mesothelioma can be easily diagnosed with a CT scan, MRI, and chest X-ray. Furthermore, a tissue biopsy (testing a sample of the affected tissue) and fluid biopsy, also known as needle aspiration (which involves inserting a needle into the affected area to collect the sample fluid), could be recommended by the doctor.
Benign mesothelioma is of four types:
• Adenomatoid Tumour (AT) Mesothelioma
• Localised Fibrous Tumour (LFT)
• Benign Multicystic Peritoneal Mesothelioma (BMPM)
• Well Differentiated Papillary Mesothelioma (WDPM)
Adenomatoid mesothelioma
Adenomatoid mesothelioma, also known as glandular or microglandular mesothelioma, affects the uterus wall and the tunica vaginalis (the pouch of serous membrane that covers the testes). In addition, it is a specific type of subset epithelial mesothelioma. Adenomatoid tumours or cells can present in both malignant and benign tissues.
Malignant mesothelioma, like pleural, pericardial or peritoneal mesothelioma, could exhibit adenomatoid growth patterns. It mimics or takes after other numerous forms of tumours, including the pleural metastases of adenocarcinoma and adenomatoid tumours. The adenomatoid cell of mesothelioma can either have a flat or cube-like shape.
Adenomatoid mesothelioma can be diagnosed with imaging scans like CT scans, X-rays, and MRIs and also through biopsies of tissue or fluid extracted from the affected area. Additionally, the benign tumour of adenomatoid mesothelioma might be incidentally diagnosed during pelvic surgery. This tumour often grows in the genitals (both in males and females), and the patient could experience symptoms like coughing and chest pain.
Asides from the genital tracts, adenomatoid tumours could also grow in parts like the adrenal glands, mesentery, liver, pancreas, bladder, and omentum. Fortunately, a surgeon can remove these tumours quite easily. Your GP can recommend treatment options like chemotherapy and radiation therapy for non-cancerous adenomatoid tumours.
Localised fibrous tumour (LFT)
This type of benign mesothelioma affects the surface of mesothelial cells in the pleura and could also occur in the pericardium, tunica vaginalis, and peritoneum. The tumours, also known as solitary fibrous, can be found in most soft tissues and organs.
The symptoms include shortness of breath, coughing, pleural effusion, and dyspnea. It's important to note that at least half of the patients with LFT do not experience symptoms. This mesothelioma can be diagnosed with computed tomography (CT) or magnetic resonance imaging (MRI) scans.
Benign multicystic peritoneal mesothelioma (BMPM)
BMPM develops in the peritoneal cavity, especially in the pelvis, and is known as multi-ocular peritoneal inclusion cysts. This form of mesothelioma is more dominant in young and middle-aged women; however, it can also grow in men and children.
The symptoms of benign multicystic peritoneal mesothelioma include pain and swelling in the abdominal area. Women of childbearing age are easily susceptible to developing BMPM. Additionally, pelvic inflammatory disease (endometriosis) or a history of previous abdominal surgery increases the risk of developing this form of benign mesothelioma.
BMPM can be diagnosed through an MRI, CT scan, ultrasonography, or a fluid biopsy. Benign multicystic peritoneal mesothelioma can be treated by completely removing the cystic tumour through surgery. However, the doctor can recommend more invasive procedures that include cytoreductive surgery alongside peritonectomy.
Additionally, your GP can attempt a laparoscopic procedure or approach. Unfortunately, a relapse of the tumour growth can occur after the treatment and complete recovery.
Well-differentiated papillary mesothelioma (WDPM)
This form of benign mesothelioma usually occurs in the peritoneum (cavity of the abdomen) and mostly in women aged 30-40 years. WDPM can also develop in the heart sac (pericardium), the tunica vaginalis (mainly in the testicular lining), and the pleura (lining of the lungs).
It is a benign mesothelioma tumour that is prone to becoming malignant. It could just be a benign tumour mixed up with malignant cells. It is a rare subtype of epithelial mesothelioma that is equally referred to as well-differentiated papillary mesothelioma. Patients might not experience symptoms but, if present, the symptoms include pain and build-up of fluid either in the abdomen or pleural.
The pain can be in the abdomen or pelvic region and ranges from acute to chronic. WDPM usually is detected or discovered during abdominal or pelvic surgery. Also, it can be diagnosed through a CT scan, other imaging tests, and tissue biopsy. CT scans cannot pick up tumours less than one centimetre in size.
Since WDPM benign can be mixed up with a malignant tumour, it can lead to a misdiagnosis. There is no known specific treatment suitable for this form of benign mesothelioma, but you can treat it with a combination of radiation, chemotherapy, and surgery. Of all the forms of benign mesothelioma and tumours, well-differentiated papillary mesothelioma is at a higher risk of turning malignant.
Other Causes Of Mesothelioma Besides Asbestos
Asbestos is known as the primary cause of mesothelioma, but in the absence of asbestos, numerous factors could cause mesothelioma or increase the risk of developing it. These factors include the following:
Exposure to erionite
Erionite is an example of the minerals referred to as zeolites. Zeolites are a group of minerals with a similar chemical composition to asbestos, especially the amosite or crocidolite family. Erionite contains sodium and calcium and occurs naturally in rock formations and deep in the soil.
Just like asbestos, erionite has a fibrous structure or fibres that could cause damage to a person's body tissues, and exposure to it could increase the risk of mesothelioma. Additionally, erionite could occur as a tight felt of fibres with a wool-like appearance.
Exposure to carbon nanotube (CNTs)
Exposure to carbon nanotubes (CNTs) is another factor contributing to mesothelioma development. Carbon nanotubes are by-products of nanotechnology, which has many applications in the electronic and medical industries.
Carbon nanotubes have physical features that are similar to asbestos. Aside from mesothelioma, exposure to the fibres of carbon nanotubes can lead to cytotoxicity and cause pleural inflammation.
Exposure to simian virus 40 (SV40)
Simian virus 40 or SV40 is a DNA polyomavirus that commonly infects Asian macaque monkeys. SV40 is considered an etiologic agent of mesothelioma in humans. Many people who received contaminated polio vaccines in the 1950s and 1960s were accidentally exposed to SV40, resulting in numerous exposure.
Exposure to SV40 does not generally produce symptoms in humans; however, it might increase vulnerability or the risk of mesothelioma.
Exposure to fluoro-edenite
Fluoro-edenite is a non-asbestos mineral fibre with morphology and composition similar to the actinolite-tremolite family of asbestos. It was reported to have been found in rock deposits of quarries located in Catania, eastern Sicily, near the city of Biancavilla.
Also, fluoro-edenite is extracted from quarries in Monte Calvario, southeast of Biancavilla. These extracted minerals are then used in manufacturing building materials for road paving, mortar construction, and commercial and residential plastering.
Cases of mesothelioma were reported in construction workers that work in these quarries near Biancavilla. Aside from mesothelioma, fluoro-edenite exposure could cause pleural plaques and equally increase the risk of pleural neoplasm.
History of chronic inflammation
This particular factor contributes primarily to malignant mesothelioma of the peritoneum or pleura (i.e., pleural and peritoneal mesothelioma). Chronic inflammations due to post tuberculosis therapeutic plombage and recurring peritonitis due to relapsing diverticulitis could increase the risk of mesothelioma and other forms of cancer.
Likewise, individuals who have Crohn's disease have a high chance of developing mesothelioma unrelated to asbestos. In addition, chronic serosal inflammatory conditions could also contribute to the development of diffuse malignant mesothelioma.
Germline BAP-1 mutational cancer
BAP-1 is a nuclear localising deubiquitinating hydrolase enzyme. The protein in BAP-1 regulates the gene responsible for cellular differentiation, cell cycle progression, and DNA damage repairs. Germline BAP-1 mutations are hereditary and can be inherited in an autosomal dominant manner.
The germline BAP-1 mutation increases the risk of mesothelioma in patients, especially individuals or families with a history of the mutation. Only a small per cent of mesothelioma cases are reported to be caused by germline BAP-1 mutations.
Families with a history of cancer are susceptible to developing mesothelioma caused by this factor. Mesothelioma caused by BAP-1 mutations has a longer life expectancy compared to the other forms of mesothelioma that are sporadic. The mesothelioma caused by this factor can be pleural or peritoneal.
Exposure to radiation
Few published reports show a link between malignant mesothelioma and radiation. Exposure of radiation (from chemotherapy) to the abdomen or chest in high doses, especially in treating another form of cancer, could lead to pleural or peritoneal mesothelioma. Additionally, one could get exposed to radiation from radiotherapy during the treatment of a childhood tumour.
Patients that undergo radiation therapy or treatment in combination with thorium dioxide administration are at higher risk of developing mesothelioma than those that don't. Asides from mesothelioma, radiation therapy might trigger new cancer like lung cancer.
Mesothelioma With/Without Asbestos Exposure
According to Cancer Council Australia, mesothelioma has a varied relationship with its various causes. Research shows a definite unit of mesothelioma not related to asbestos exposure, with pleural and peritoneal mesothelioma falling under this category.
Mesothelioma is more common in men (mostly construction workers) than in women due to occupational exposure to minerals that could increase the risk of it. On the other hand, women also experience second-hand exposure to these minerals at home. In addition, secondary asbestos exposure could worsen the effects of these non-asbestos mesothelioma contributing factors.
Also, age and the geographical location of the patients is another contributing factor to asbestos-unrelated mesothelioma. Consequently, it's important to see professional medical assistance if you experience any of the symptoms of mesothelioma mentioned above, even if you have not been exposed to asbestos.
Moreover, should you suspect the presence of asbestos on your property, it is vital to have a specialised asbestos removalist perform the removal. Such countermeasures will ensure that you are not unnecessarily exposed to asbestos, leading to health risks like mesothelioma down the line.
David
