What are the other Names for this Condition? (Also known as/Synonyms)

• MEC of Lung
• Mucoepidermoid Tumour of Lung
• Pulmonary Mucoepidermoid Tumor

What is Mucoepidermoid Carcinoma of Lung? (Definition/Background Information)

• Mucoepidermoid Carcinoma (MEC) of Lung is an uncommon type of lung cancer of the epithelial cells. It is classified as a salivary-gland type tumor. The tumor can be either a low-grade carcinoma or a high-grade carcinoma
• There is no known risk factor for Mucoepidermoid Carcinoma of Lung. It has been diagnosed among a wide age range of individuals, up to the age of 80 years
• Mucoepidermoid Carcinoma of Lung can present with chest pain, breathing difficulties, and other general signs and symptoms, such weight loss and fatigue
• The prognosis is dependent on the severity of tumor. Some Mucoepidermoid Carcinomas of the Lung are low-grade, and children diagnosed with the tumor, generally have a good prognosis

Who gets Mucoepidermoid Carcinoma of Lung? (Age and Sex Distribution)

• Mucoepidermoid Carcinoma of Lung comprises less than 1% of all lung cancers. Some studies show this value to be between 0.1-0.3%
• Half of all incidences are observed among individuals, younger than 30 years of age. The highest concentration of diagnosis is seen in the age group of 30-40 years. A wide age range of 0-80 years is observed
• Both males and females are affected and no particular preference is observed
• All racial and ethnic groups may be affected. But, this tumor is more common in Caucasians than other dark-skinned individuals
• A significant proportion of children diagnosed with pediatric endobronchial tumors have Mucoepidermoid Carcinoma of Lung

What are the Risk Factors for Mucoepidermoid Carcinoma of Lung? (Predisposing Factors)

• There is no known risk factor for typical Mucoepidermoid Carcinoma of Lung
• An association of the tumor with smoking is not observed

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mucoepidermoid Carcinoma of Lung? (Etiology)

The exact cause of Mucoepidermoid Carcinoma of Lung is unknown. The development of this carcinoma is not associated with smoking, unlike most other types of lung cancer.

• The presence of CRTC1-MAML2 gene fusion has been reported in both high-grade and low-grade mucoepidermoid carcinomas (similar to those found in salivary gland-type tumors)
• Some tumor specimens have demonstrated the presence of EGFR gene mutations. However, the significance of this finding is not well understood
• In general, it is known that cancers form when normal, healthy cells begin transforming into abnormal cells - these cancer cells grow and divide uncontrollably (and lose their ability to die), resulting in the formation of a mass or a tumor
• The transformation of normally healthy cells into cancerous cells may be the result of genetic mutations. Mutations allow the cancer cells to grow and multiply uncontrollably to form new cancer cells
• These tumors can invade nearby tissues and adjoining body organs, and even metastasize and spread to other regions of the body

What are the Signs and Symptoms of Mucoepidermoid Carcinoma of Lung?

Early-stage Mucoepidermoid Carcinoma of Lung may display no significant signs and symptoms. Also, the early symptoms may be similar to those associated with common benign lung conditions, which makes for a difficult diagnosis at an early stage. The symptoms displayed are mostly caused due to irritation and/or obstruction of the trachea and airways.

Signs and symptoms associated with Mucoepidermoid Carcinoma of Lung may include:

• Wheezing
• Hemoptysis: Blood in cough is the most common sign
• Coughing
• Weight loss
• Labored breathing
• Fatigue
• Pain in the chest
• Pneumonia, due to obstruction of the airways, in 75% of the cases
• In case of metastasis, pain at metastatic sites, such as the bone

The tumor is usually located centrally (endobronchial location) and presents as a well-defined mass. The tumor size is around 3 cm (average size). Later stage tumors may involve the local and distant lymph nodes. High-grade tumors may infiltrate into local areas, more than the low-grade mucoepidermoid carcinoma.

How is Mucoepidermoid Carcinoma of Lung Diagnosed?

There are a variety of tests physicians may use to detect, locate, and diagnose Mucoepidermoid Carcinoma of Lung and to examine if it has potentially spread to other regions. These include the following:

• Physical examination: During a physical exam, a physician will check the individual’s overall health status, listen to their breathing, and check for possible fluid buildup in the lungs (auscultation)
• Detailed medical history evaluation

Mucoepidermoid Carcinoma of Lung is observed as an oval or lobular mass in the bronchus on a CT scan or chest radiograph. A surgical procedure called a biopsy (usually performed by a radiologist or a cardiothoracic surgeon), is the only test a physician uses in order to make a definitive diagnosis of the condition.

However, if a physician is unable to perform a lung biopsy due to the risk of damaging vital organs, additional tests will be recommended, and these may include:

• Chest X-ray: Two-dimensional pictures using tiny amounts of radiation are taken, in order to detect any tumors or other medical issues associated with the lungs, such as pneumonia. Tumors inside the lung, including Mucoepidermoid Carcinoma of the Lung, which is usually on the periphery, can be detected using a chest X-ray; although sometimes, these tumors are too small to visualize
• Computerized tomography (CT) scan: Also known as CAT scan, this radiological procedure creates detailed three-dimensional images of structures inside the body. CT scans are not a tool of preference to detect Mucoepidermoid Carcinoma of the Lung; although, CT scans may be helpful in detecting recurrences, or if the cancer has metastasized to the surrounding lymph nodes of the lungs
• Positron emission tomography (PET): A PET scan is a nuclear medicine imaging technique that uses three-dimensional images to show how tissue and organs are functioning. A small amount of radioactive material may be injected into a vein, inhaled or swallowed. A PET scan is also helpful in detecting recurrences, or if any metastasis (to the surrounding lymph nodes of the lungs) has occurred
• Magnetic resonance imaging (MRI): An MRI scan uses magnetic fields that create high quality pictures of certain body parts, such as tissues, muscles, nerves, and bones. These high-quality images may indicate to a physician if any MEC of Lung is present
• Sputum cytology: Sputum cytology is test that involves the collection of mucus (sputum), coughed-up by a patient. After the mucus is collected, a pathologist examines in an anatomic pathology laboratory, if any cell abnormalities are present indicative of the cancer
• Bone scan: A bone scan is a nuclear imaging test that involves injecting a radioactive tracer into an individual’s vein. Bone scans are primarily used to detect, if the cancerous cells in the tumor have metastasized to the bones and formed secondary tumors
• Bone marrow biopsy: Bone marrow is a soft tissue found within bones. Occasionally, with the tumor, a bone marrow biopsy is used to detect blood abnormalities, or if a physician thinks that metastasis to the bone marrow may have occurred

A biopsy refers to a medical procedure that involves the removal of cells or tissues, which are then examined by a pathologist. Different biopsy procedures include:

• Bronchoscopy: During bronchoscopy, physicians’ use a special medical instrument called a bronchoscope, which is inserted through the nose and into the lungs to collect small tissue samples. These samples are then examined by a pathologist, after the tissues are processed, in an anatomic pathology laboratory
• Thoracentesis: During thoracentesis, physicians use a special medical device called a cannula, to remove fluid between the lungs and the chest wall. A pathologist then examines the extracted cells from the fluid, in an anatomic pathology laboratory to determine any signs of Mucoepidermoid Carcinoma of Lung
• Thoracoscopy: During thoracoscopy, a surgical scalpel is used to make very tiny incisions into the chest wall. A medical instrument called a thoracoscope is then inserted into the chest, in order to examine and remove tissue from the chest wall, which are then examined further
• Thoracotomy: Thoracotomy is a surgical invasive procedure with special medical instruments to open-up the chest. This allows a physician to remove tissue from the chest wall or the surrounding lymph nodes of the lungs. A pathologist will then examine these samples under a microscope after processing the tissue in a laboratory
• Mediastinoscopy: During mediastinoscopy, a surgical scalpel is used to make very tiny incisions above the breastbone. Then, a medical instrument called a mediastinoscope is inserted into the chest wall to examine and remove samples. These tissue samples are processed and then examined under a microscope for any abnormalities
• Fine needle aspiration biopsy (FNAB): During fine needle aspiration biopsy, a device called a cannula is used to extract tissue or fluid from the lungs, or surrounding lymph nodes. These are then examined in an anatomic pathology laboratory, in order to determine any signs of Pulmonary MEC
• Autofluorescence bronchoscopy: It is a bronchoscopic procedure in which a bronchoscope is inserted through the nose and into the lungs and measure light from abnormal precancerous tissue. Samples are collected for further examination by a pathologist

A differential diagnosis with respect to other lung cancer types may be necessary prior to establishing a definite diagnosis, by excluding the following cancers:

• Poorly-differentiated carcinomas affecting the lung (including squamous cell carcinoma and its histological variants)
• Acute leukemia
• Adenosquamous carcinoma
• Ewing’s sarcoma
• Germ cell tumors that have spread to the lungs
• Small cell carcinoma
• Undifferentiated carcinomas

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mucoepidermoid Carcinoma of Lung?

Complications of Mucoepidermoid Carcinoma of Lung include:

• Dyspnea (shortness of breath): Individuals may have an increased risk of exhibiting signs of dyspnea, if the cancerous tumor expands to block important large or small airways of the chest or lung
• Hemoptysis (coughing-up blood): Individuals may cough-up blood, due to excessive amounts of blood in the airways
• Pain: Advanced stages of the tumor that has metastasized to the pleural cavity (lining surrounding the lungs), invaded the chest wall, or other areas of the body, may cause excessive pain and agony
• Pleural effusion (fluid in the chest): Excessive fluid accumulation, resulting from cancerous cells of mucoepidermoid carcinoma spreading inside the lungs, or outside of the lungs
• Mucoepidermoid Carcinoma of Lung that spreads to other parts of the body: There is an increased risk of the cancer metastasizing (or spreading) to other parts of the body, such as the adrenal gland, liver, bones, and to the unaffected lung

How is Mucoepidermoid Carcinoma of Lung Treated?

As with most cancers, early detection is linked with better survival results. The treatment method used is dependent on the location of the tumor, its type, and the stage of cancer. For Mucoepidermoid Carcinoma of the Lung, surgery is the most commonly used and most effective form of treatment.

Low-grade Mucoepidermoid Carcinoma of Lung is often resected with sleeve resection, or other bronchoscopic procedures. The treatment to high-grade Mucoepidermoid Carcinoma of Lung is similar to non-small cell carcinoma. Chemotherapy and radiation therapy are used in cases of metastasis and/or when surgery is not a viable option.

• Chemotherapy: Chemotherapy drugs are typically taken as pills, or injected directly into a vein. These drugs travel through the body to kill any cancer cells. But, they can also kill healthy cells, located within the gastrointestinal tract and in hair follicles. The side effects include vomiting, nausea, and hair loss
• Radiation therapy: Radiation therapy involves using x-rays to kill cancerous cells. High-powered radiation beams are directed to particular body regions to target cancer. In the process, healthy cells can also be damaged. Radiation therapy can be administered in the following ways:
  • Either by a machine, placed outside the body (called external beam radiation)
  • Or it may be administered internally, by a device positioned directly at, or close to the malignant tumor, inside the lungs (called brachytherapy)

Radiation therapy and chemotherapy can be used as a combination therapy. Combinational therapy increases the effects of both types of treatment. However, the side effects are cumulative. Combined therapy is mostly used in cases with metastasis, or when surgery is not a viable option.

Surgery: Depending on the stage of MEC of Lung, surgery might be a viable option. However, the location of the tumor in the periphery makes it commonly associated with metastasis. The surgical options include:

• Wedge resection: Wedge resection is a partial removal of the wedge-shape portion of the lung that contains cancerous cells (along with any surrounding healthy tissue)
• Segmentectomy: Segmentectomy is also the partial removal of the cancerous lung and any surrounding healthy tissue
• Lobectomy (pulmonary lobectomy): Lobectomy is the most common type of surgical procedure performed for Mucoepidermoid Carcinoma of Lung, to partially remove a portion of a lung
• Sleeve lobectomy: Sleeve lobectomy is also a surgical procedure to partially remove a portion of the lung and a part of the airway (bronchus)
• Pneumonectomy: It is the surgical removal of the entire lung

Some individuals with Mucoepidermoid Carcinoma of Lung showing mutation in the EGFR (epithelial growth factor receptor) gene and respond well with the targeted therapy drug Gefitinib.

How can Mucoepidermoid Carcinoma of Lung be Prevented?

There are no known risk factors for Mucoepidermoid Carcinoma of the Lung, and there is no known method to prevent its occurrence. Although there are no preventable measures for lung cancer, in general, various steps can be taken to help decrease the risk of its formation. These measures include:

• Complete smoking cessation and avoiding exposure to secondhand smoke: The risk for lung cancer decreases drastically following quitting or giving up smoking
• Physical activity: Individuals, who participate in a moderate amount of physical activity, may decrease their risk
• Adequate consumption of fruits and vegetables: A healthy diet, low in saturated fats and rich in many fruits and vegetables, may help decrease one’s risk for lung cancer
• Avoid exposure to certain materials and chemicals (including asbestos, arsenic, chromium, nickel, and tar): Individuals who work with such substances should follow proper usage principles and occupational safety instructions, since a prolonged exposure to harmful chemicals may increase the risk for lung cancer. This risk is multiplied in smokers who are exposed to these harmful chemicals
• Avoid exposure to radioactive gas: Radon, a radioactive gas, produced by the natural breakdown of uranium in soil and rocks, may develop to hazardous levels inside building spaces. Individuals exposed to excessive amounts of radon gas are vulnerable to lung cancer
• Limit alcohol consumption: Alcoholic beverages have been linked to increasing an individual’s risk for certain types of cancers, such as those affecting the lungs, mouth, throat, esophagus, breast, colon, and liver
• CT screening in high-risk groups can decrease the incidence of lung cancer, or at least help detect such cancers early. A low-dose CT scan is good to identify the tumors early. It is generally known that CT scans are about 3-4 times better than X-ray studies

What is the Prognosis of Mucoepidermoid Carcinoma of Lung? (Outcomes/Resolutions)

• The prognosis of typical Mucoepidermoid Carcinoma of Lung depends on the stage at which it is diagnosed (whether it is high-grade or low-grade), and the presence of metastasis, if any
• Metastasis to regional lymph node is observed in less than 5% of low-grade Mucoepidermoid Carcinoma of Lung, with rare distant metastasis. In high-grade tumors, metastasis to adrenal glands, liver, brain, and bone, is indicative of a poor prognosis
• The overall prognosis with post-surgical resection is good, with the 5-year and 10-year survival rates, reported in literature, being 87-97.6% and 86.7% respectively.

Mucoepidermoid Carcinoma of Lung is staged as follows:

• Stage I: The tumor is only in the lung
• Stage II: The tumor is in the lung and has metastasized to adjacent lymph nodes
• Stage IIIA: The tumor is in the lung and the lymph nodes, on the same side of the chest, as the cancer
• Stage IIIB: The tumor is in the lung and the lymph nodes, on the opposite side of the chest as the cancer, or is above the collar bone
• Stage IV: The tumor has spread to other side of the lung and other parts of the body

Other prognostic indicators include:

• Children have better prognosis and a more benign disease course
• Positive tumor margin and lymph node involvement/metastasis are associated with poor prognosis

The prognosis of lung cancer, in general, depends upon a set of several factors that include: 

• The grade of the lung tumor such as grade1, grade2, and grade 3. Grade1 indicates a well-differentiated tumor, grade 2 a moderately-differentiated tumor, whereas grade 3 indicates a poorly-differentiated tumor. Grade 3 tumors are higher prone to metastasis to the lymph nodes and recurrence
• Stage of lung cancer: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy. In higher-stage tumors, such as tumors with metastasis, the prognosis is poor
• Histological subtype of the tumor: Some subtypes have better prognosis than others
• The size of the lung tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
• Overall health of the individual: Individuals with overall excellent health have better prognosis compared with those with poor health
• Age of the individual: Older individuals generally have poorer prognosis than younger individuals
• Individuals with bulky disease of the lung cancer have a poorer prognosis
• Involvement of the lymph node, which can adversely affect the prognosis
• Involvement of vital organs may complicate the condition
• The surgical respectability of the tumor (meaning, if the tumor can be removed completely)
• Whether the tumor is occurring for the first time, or is a recurrent tumor. Recurring tumors have worse prognosis compared to tumors that do not recur
• Response to treatment of lung cancer: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment
• Progression of the condition makes the outcome worse

Furthermore, as with other forms of cancer, early detection is correlated with higher survival rates. For patients diagnosed with Mucoepidermoid Carcinoma of Lung, it is important to have follow-up appointments with a physician, to evaluate the effects of the current treatment method, and to monitor for any returning tumors.

Additional and Relevant Useful Information for Mucoepidermoid Carcinoma of Lung:

Mucoepidermoid Carcinoma of Lung involves squamous cells (a subtype of epithelial cells), mucin-secreting cells and intermediate cells and is detected by the pathologist, when tissue is examined under a microscope.