Key takeaways

  • Mucinous carcinoma is a rare type of cancer that primarily develops in the breast.
  • Treatment typically involves surgery to remove the tumor, such as a lumpectomy or mastectomy. It may also include hormone therapy, which proves particularly effective for this cancer type, along with chemotherapy when necessary.
  • Regular breast self-examinations and mammograms can help with detection. Screenings for other types of cancer are also important.

Mucinous carcinoma is a type of invasive cancer in which mucin — the main component of mucus — surrounds the cancer cells.

Mucinous carcinoma is an invasive cancer, meaning that it can spread to other parts of the body. However, it is less aggressive than other invasive types of cancer, and it generally responds well to treatment.

Less commonly, mucinous carcinoma first develops in areas other than the breast, such as the colon or rectum.

Read on to learn more about mucinous carcinoma, including the symptoms and causes, treatment options, and more.

Symptoms of mucinous carcinoma can depend on where the tumor develops.

Breast cancer

Initially, mucinous carcinoma of the breast may not cause symptoms.

As the cancer develops, a lump may form in the breast tissue, and a person may eventually be able to feel it during an examination.

On average, a mucinous carcinoma tumor measures 3 centimeters, though the size can vary widely.

Breast cancer symptoms besides a lump can include:

  • armpit pain
  • breast pain
  • changes to breast size or shape
  • nipple changes
  • nipple discharge
  • puckering or dimpling of the skin on the breast
  • swelling under the arm

Colorectal cancer

Colorectal cancer symptoms can include:

Lung cancer

The symptoms of mucinous carcinoma of the lung are the same as those of other types of lung cancer. They can include:

Mucinous carcinoma may cause other symptoms if it develops in other parts of the body. It is important to report any new or changing symptoms to a healthcare professional for evaluation.

Mucinous carcinoma causes and risk factors can depend on the type of cancer.

Breast cancer

For mucinous carcinoma of the breast, causes and risk factors are similar to those of breast cancers in general. It is likely that a combination of genetics and environmental factors leads to the cancer developing.

Genetic mutations can lead to mucinous carcinoma. However, as a 2020 review notes, this type of cancer has fewer genetic mutations compared with ductal and lobular breast cancer.

The review also explains that mucinous carcinoma of the breast is more common in women, particularly after menopause.

Colorectal cancer

The risk factors for colorectal mucinous carcinoma are typically the same as those for colorectal cancer in general.

Risk factors can include:

  • a lack of physical activity
  • consuming a diet high in red and processed meats
  • tobacco use
  • moderate to heavy alcohol use
  • diabetes
  • obesity
  • a family history of colorectal cancer
  • a personal history of colorectal cancer

Lung cancer

The risk factors for mucinous carcinoma of the lung are typically the same as those for other lung cancers.

Risk factors can include:

  • tobacco use
  • exposure to secondhand smoke
  • exposure to chemicals that cause cancer, such as asbestos, arsenic, and radon
  • a family history of lung cancer

To assist with reaching an accurate diagnosis, a healthcare professional may begin by asking questions and performing a physical examination.

Tests will be necessary to confirm the diagnosis. Tests to help diagnose breast cancer can include:

Tests for colorectal cancer can include:

Tests for lung cancer can include:

This type of cancer can form alongside other cancer cells, such as those of ductal breast cancer. When this happens, doctors refer to it as “mixed mucinous carcinoma.”

By contrast, “pure” mucinous carcinoma has 90% mucinous cells.

Treatment for mucinous carcinoma depends on the type and stage of the cancer, the person’s health status, and the affected area of the body.

Surgery

The aim of surgery is to remove the cancerous cells and any affected lymph nodes.

When treating mucinous carcinoma of the breast, the surgeon may remove part or all of the breast tissue.

Chemotherapy

Chemotherapy involves taking medications to destroy cancer cells that may be present outside the main lump.

Hormone therapy

Hormone therapy can help lower the risk of the cancer returning.

Hormone therapy aims to reduce the amount of estrogen in the body or block its effects. This type of treatment can be effective for hormone-positive breast cancers.

Mucinous carcinoma of the breast tends to have a better outlook than invasive ductal carcinoma. The outlook is also better for pure mucinous carcinoma compared with mixed mucinous breast carcinoma.

The survival rate can depend on many factors, such as the type and stage of the cancer, how effective treatment is, and the overall health of the individual.

A person’s doctor can provide them with information about their outlook based on individual circumstances.

Mucinous carcinoma is a rare type of cancer. It usually develops in the breast, but it may also develop in other parts of the body, such as the lungs, colon, or rectum.

It is important for a healthcare professional to detect and treat the cancer as early as possible. Regular breast self-exams, mammograms, and other screenings can help.

It is also helpful to reduce cancer risk factors whenever possible, such as by avoiding tobacco smoke, getting enough physical activity, and avoiding a diet high in red or processed meats.

Contact a healthcare professional as soon as there are concerns about the symptoms of cancer. It is also best to speak with a healthcare professional for information on when they recommend routine screenings.