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

• Mammary Mucoepidermoid Carcinoma
• MEC of Breast

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

• Breast cancer is the most common type of cancer diagnosed in women. It is a type of cancer in which certain cells in the breast become abnormal, grow uncontrollably, and form a malignant mass (tumor). There are various types of breast cancers
• Mucoepidermoid Carcinoma of Breast is an extremely rare type of invasive breast carcinoma. This histological subtype is diagnosed when the tumor cells are observed under the microscope by a pathologist. This form of cancer is observed in middle-aged and older adults
• The mucoepidermoid carcinoma (MEC) subtype is frequently described in the salivary gland but is very rare in the breast. The breast is sometimes regarded as a modified apocrine (sweat) gland, a type of salivary gland; functionally breasts produce milk, and structurally they are considered to be modified sweat glands. MEC is also described in the lung, bronchus, esophagus, and thyroid gland
• The cause of development of Mucoepidermoid Carcinoma of Breast is not well-established. Many genetic abnormalities have been reported, although these are presently not well-characterized. The condition can cause a breast mass, nipple discharge, and other signs and symptoms. The carcinoma may be diagnosed via breast biopsy
• Since MECs are very rare tumors in the breast, there are no well-defined treatments available for the condition. The treatment provided for Mucoepidermoid Carcinoma of Breast is often on a case-by-case basis using modalities such as surgery, radiation therapy, and chemotherapy
• The prognosis depends on many factors, but chiefly on the tumor grade. Since there is a risk for recurrence and metastasis, close clinical monitoring is necessary with periodic follow-ups. An early diagnosis and adequate treatment can significantly improve the outcomes

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

• Mucoepidermoid Carcinoma of Breast is a highly uncommon tumor with less than 50 cases being reported in the literature. The incidence rate of MEC is about 0.2% of all breast cancers
• It is generally observed in adult women in the 29 to 86 years’ age range
• All racial and ethnic groups are affected, and no specific predilection is seen

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

The risk factors for Mucoepidermoid Carcinoma of Breast are not well established since the condition is rare. In general, the risk factors for developing breast cancer may include:

• Women have a much greater chance of developing breast cancer than men
• Age: The risk increases for women over the age of 55 years
• Personal history: Having cancer in one breast, puts a woman at risk for having cancer in the other breast as well
• Family history: Women with a mother, sister, or daughter diagnosed with breast cancer have a higher risk for developing the condition
• Inherited gene mutations: Mutations in certain genes (BRCA1 or BRCA2) can lead to a much higher risk
• Radiation therapy: Receiving radiation therapy to the chest or breast area can also increase the risk. It is noted that the risk for developing breast cancer later in life is the greatest for radiation therapy administered during puberty
• Obesity: Being overweight or obese elevates the risk after menopause
• Alcohol use: Consuming alcohol more than one drink per day; the more the alcohol consumed, the greater is the risk
• Menstrual cycle: Women who got their period before the age of 12 years, and those who reached menopause after age 55 have an increased risk
• Postmenopausal hormone therapy: Women taking hormone replacement therapy medications containing both estrogen and progesterone for menopause have a higher risk of developing breast cancer
• Reproductive history: Having the first child after the age of 35, or never having children
• Physical inactivity: A lack of physical exercise (leading a sedentary life) can increase the risk
• Breastfeeding: Not breastfeeding one's child can increase the risk for developing the condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s 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 Breast? (Etiology)

The exact cause of development of Mucoepidermoid Carcinoma of Breast is currently not well understood. It is suggested that certain genetic factors may have a role in their formation, although these are not well-characterized.

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

The signs and symptoms of Mucoepidermoid Carcinoma of Breast are similar to those of other invasive breast carcinomas and may include:

• A growing mass that may be cystic or solid in nature
• The size of the tumor mass may vary from 0.5 to 11 cm (averaging 3.4 cm)
• Discharge from the nipple
• Thickening or swelling of part of the breast; change in the size or shape of the breast
• Inversion of the nipple (pulling-in of nipple into the breast) 
• Changes to the skin covering the breast or nipple area, including dimpling, irritation, redness, scaling, peeling, or puckering 
• The condition can be unilateral (involving only one breast) or bilateral (affecting both breasts)

MEC may be categorized as low-grade, intermediate-grade (rarely), or high-grade.

How is Mucoepidermoid Carcinoma of Breast Diagnosed?

Mucoepidermoid Carcinoma of Breast may be diagnosed in the following manner:

• Complete physical examination with comprehensive medical and family history evaluation
• Breast exam to check for any lumps or unusual signs in the breasts
• Blood tests including complete blood count (CBC) test
• Mammogram: A mammogram uses X-rays to provide images of the breast
• Galactography: A mammography using a contrast solution, mostly used to analyze the reason behind a nipple discharge
• Breast ultrasound scan: Using high-frequency sound waves to produce images of the breast
• Computerized tomography (CT) or magnetic resonance imaging (MRI) scan of the breast
• Positron emission tomography (PET) scan to help determine, if the cancer has spread to other organ systems
• Breast biopsy:
  • A biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
  • Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
  • Sometimes, the pathologist may perform additional studies, which may include immunohistochemical stains and molecular studies to assist in the diagnosis

Biopsies are the only methods used to determine whether an abnormality is benign or cancerous. These are performed by inserting a needle into a breast mass and removing cells or tissues, for further examination. There are different types of biopsies:

• Fine needle aspiration biopsy (FNAB) of breast mass: In this method, a very thin needle is used to remove a small amount of tissue
• Core needle biopsy of breast mass: A wider needle is used to withdraw a small cylinder of tissue from an abnormal area of the breast
• Open tissue biopsy of breast mass: A surgical procedure used less often than needle biopsies, it is used to remove a part or all of a breast lump for analysis

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 Breast?

The complications of Mucoepidermoid Carcinoma of Breast may include:

• Emotional distress due to the presence of breast cancer
• Recurrences following surgery may be observed; incompletely excised tumors may recur
• Metastasis of the tumor to local and regional sites
• Treatment side effects

How is Mucoepidermoid Carcinoma of Breast Treated?

Treatment options available for individuals with breast cancer are dependent upon the following:

• Type of cancer
• The staging of the cancer: If a breast cancer is diagnosed, staging helps determine whether it has spread, and what treatment options are best-suited for the patient
• Whether the cancer cells are sensitive to certain particular hormones, and
• One’s personal preferences

Nevertheless, since Mucoepidermoid Carcinoma of Breast is a very rare tumor, there are no standard treatment protocols established to manage the condition. The treatment provided is based on the evaluation of the healthcare provider and can vary from one individual to another.

Surgery: Surgery is generally the most common form of treatment involving the removal of the tumor. Various types of surgery to remove the malignant tumor include:

• Lumpectomy: Breast-sparing surgery (least invasive breast cancer surgery) in which the tumor, as well as a small portion of the surrounding tissue is removed
• Mastectomy: Surgery to remove all of the breast tissue; it may be simple (removal of the breast, nipple, areola, sentinel lymph nodes) or radical mastectomy (removal of the breast, nipple, areola, all axillary lymph nodes, and underlying muscle of the chest wall)
• Sentinel node biopsy: Procedure done to examine the “sentinel lymph node,” or lymph node(s) closest to the tumor, as this is the most likely location, where cancer cells may have spread to. This lymph node is removed and tested for cancerous cells
• Axillary node dissection: This procedure is performed to remove some axillary lymph nodes in the underarm area, to allow dissection and examination. This helps in establishing whether the cancer has spread to more than one lymph node

Other treatment options may include chemotherapy and radiation therapy.

• Radiotherapy can be used as primary therapy in situations where the tumor cannot be removed completely, or when the tumor reappears after surgery
• Radiotherapy can also be used as additional therapy after surgery, if there is a possibility of tumor recurrence after surgery, or if there are inadequate margins (possibility of tumor left behind) following surgery. In some cases, due to location of tumor, a complete surgical removal of the tumor is difficult
• Chemotherapy can be used for treating the tumor in the following conditions
  • When the tumors cannot be removed completely (due to incomplete surgical resection)
  • Tumors that recur after surgery
  • Tumors that have spread to distant parts of the body 

How can Mucoepidermoid Carcinoma of Breast be Prevented?

Currently, no specific preventive measures are available for Mucoepidermoid Carcinoma of Breast. In general, it is important to be aware of the following:

• Learning to do regular ‘breast self-exams’ in order to help identify any unusual lumps or signs in the breast
• Maintain a healthy body weight and exercise regularly
• Implement and follow a well-balanced diet; a high intake of fiber via fresh fruits and vegetables helps in a healthy lifestyle
• Avoid or completely stop smoking
• If taking alcohol, only drink in moderation; limit to one or (maximum) two drinks a day
• Limit combination hormone therapy used to treat symptoms of menopause. It is advised that individuals be aware of the potential benefits and risks of such hormonal medications
• Cancer screenings can help detect any breast cancer during the early stages

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

• Mucoepidermoid Carcinoma of Breast is an extremely rare form of breast cancer. The prognosis of the condition depends upon several factors and can vary from one individual to another
• However, grading a very critical prognostic factor; individuals with low and intermediate tumor grades have better overall prognosis than those with high tumor grades
• The prognosis of breast cancer, in general, depends upon a set of several factors that include: 
  • The grade of the breast tumor
  • The size of the breast tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
  • Stage of breast 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
  • Cell growth rate
  • 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 breast 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 resectability 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 breast 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
• An early diagnosis and prompt treatment of the tumor generally yields better outcomes than a late diagnosis and delayed treatment
• The combination chemotherapy drugs used, may have some severe side effects (like cardio-toxicity). These chiefly impacts the elderly adults, or those who are already affected by other medical conditions. Tolerance to the chemotherapy sessions is a positive influencing factor

Additional and Relevant Useful Information for Mucoepidermoid Carcinoma of Breast:

The following DoveMed website links are useful resources for additional information:

https://www.dovemed.com/healthy-living/womens-health/

https://www.dovemed.com/diseases-conditions/cancer/