What is Mucinous Breast Carcinoma?
Mucinous carcinoma of the breast is a less common type of breast cancer, making up about 2% of all breast cancers. According to the latest World Health Organization (WHO) guidelines, this is classified as a unique kind of breast cancer. There are two subtypes of this cancer based on the structure of the tumor:
- Pure type mucinous carcinoma.
- Mixed type mucinous carcinoma.
The pure type is made up only of tumor tissue that produces a substance called mucin in over 90% of the tumor. On the other hand, the mixed form also has a ductal epithelial component, parts of the tissue affected by cancer that don’t produce mucin. Mucinous breast cancer generally has a positive outlook with a low recurrence rate and low chances of spreading to lymph nodes. The confirmed diagnosis and categorization of mucinous breast cancers mainly rely on an examination of the tissue structure.
What Causes Mucinous Breast Carcinoma?
Mucinous breast cancer comes about from many factors working together. These include what you eat, your reproductive health and hormones. Mucinous breast cancer doesn’t just have one cause; it involves a mix of lifestyle and biological elements.
Risk Factors and Frequency for Mucinous Breast Carcinoma
Mucinous breast carcinoma, a type of breast cancer, typically occurs in women who are postmenopausal, with the average age being 70. However, it very rarely impacts young patients under the age of 35.
Signs and Symptoms of Mucinous Breast Carcinoma
Mucinous carcinoma is a type of cancer that typically grows slowly and is often quite large when it is diagnosed. This happens because the cancer is filled with a substance called mucin which does not feel hard or solid when the area is examined. Many people with this condition notice a lump in their breast. It’s rare, but in very large cases, this lump may feel attached to the skin or chest wall. A lot of the time, this condition is diagnosed during routine mammograms that spot something unusual.
Testing for Mucinous Breast Carcinoma
In mammograms, certain findings, such as smooth or round breast abnormalities, often point towards mucinous carcinoma, a type of breast cancer. The more these mamogram findings are present, the more likely it is that the patient has pure mucinous carcinoma.
When we perform an ultrasound, a type of imaging that uses sound waves to create images of your breasts, we often see a complex mass- a structure that contains both cystic (fluid-filled) and solid components if you have mucinous carcinoma. This mass may have an uneven surface, show blood supply, and make a backwave. Ultrasound can even help us predict the subtype of mucinous carcinoma: masses that have the same level of brightness (or ‘echogenicity’) as the surrounding tissue suggest pure mucinous carcinoma, whereas darker masses suggest mixed mucinous carcinoma.
MRI, or magnetic resonance imaging, provides another way for us to look at your breasts, with mucinous carcinoma typically appearing as a lobular (oval or round) shape. It may also appear as an enhancing rim or region of differing enhancement, exhibit a stable pattern over time on a time-intensity curve, and give off a strong, evenly distributed signal in T2-weighted images, which are images that are sensitive to water in your body.
A tissue biopsy, which involves sampling a piece of your breast tissue, is a must for identifying mucinous breast carcinoma. Tissue samples can be obtained using several methods including core biopsy (using a large needle), fine needle aspiration cytology (using a thin needle), and incisional or excisional biopsy (surgical removal of part or all of the lump).
Treatment Options for Mucinous Breast Carcinoma
Mucinous breast carcinoma, a type of breast cancer, is typically treated with a combination of surgery and hormone therapy post-surgery, especially when the tumor is responsive to hormones (ER/PR). Recent research suggested a series of steps for treatment which include identifying the stage of the cancer through a procedure called sentinel lymph node biopsy, followed by radiation therapy and hormone therapy after breast-saving surgery.
Most mucinous carcinomas do not produce a protein called HER2/neu. As such, a drug called trastuzumab, which is usually used to treat breast cancers that do produce this protein, is not typically used in treating mucinous carcinoma.
Some researchers suggest that additional chemotherapy after surgery can be skipped in cases where the risk factors are favorable – in other words, when the test results and patient factors predict a lower risk of the cancer coming back.
What else can Mucinous Breast Carcinoma be?
The medical experts consider a few alternatives when making a diagnosis based on tissue sample examination. These include:
- Mucocele-like-lesion
- Metastatic mucinous carcinoma
Also, when interpreting medical imaging, other conditions may look similar. These are:
- Myxomatous fibroadenoma
What to expect with Mucinous Breast Carcinoma
Mucinous carcinoma, a type of breast cancer, generally has a good outlook and doesn’t often spread to the lymph nodes, especially when compared to invasive ductal carcinoma, another type of breast cancer. This means that the cancer cells spread from the original tumor to nearby lymph nodes, a process referred to as axillary lymph node metastases, in only about 12%-14% of cases.
Pure mucinous carcinoma, where the tumor is made up completely of mucinous cells, usually has a better prognosis than mixed mucinous breast carcinoma where other types of cells are also present in the tumor. After five years, 81-94% of people diagnosed with this type of cancer remain disease-free, with the higher percentage pertaining to those where the cancer has not spread to the lymph nodes.
Though rare, the cancer can sometimes spread to other parts of the body, a process referred to as distant metastases. Interestingly, researchers have looked into what factors might predict the likelihood of the disease progressing. They analyzed data from 11,422 patients and found that the size of the original tumor was an important indicator, although the status of the lymph nodes (whether or not the cancer had spread to them) was actually more significant.
However, other studies suggest that the size of the tumor may not be that important for predicting a person’s outlook, as most of the tumor volume consists of mucin – a slimy, gel-like substance produced by the mucinous cells.
Possible Complications When Diagnosed with Mucinous Breast Carcinoma
Complications of a specific type of breast cancer called mucinous carcinoma can include:
- Spread of the cancer to lymph nodes located in the armpit
- Development of cancer in other parts of the body long after the initial diagnosis
- Return of the cancer after being surgically removed
Preventing Mucinous Breast Carcinoma
Women who are 40 years old and older should have a chat with their doctor about the pros and cons of breast cancer screening, and decide when to start getting tested. The mammogram, a test used to check for breast cancer, can be offered to women from ages 40 to 74, or even older if the woman is healthy. For women at high risk of breast cancer (for example, those with the BRCA gene or those who have immediate family members with breast cancer), screening might need to start earlier.
It’s also worth noting that just because a mammogram test result is abnormal, it doesn’t automatically mean that the woman has breast cancer. Statistics show that 9 out of 10 women who come back with unusual mammogram results do not end up having breast cancer.
A lot of specialist advice revolves around getting a mammogram test done every two years. This of course should be in consultation with your medical professional based on your personal health and family history.
