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Mucinous breast cancer

Find out more about mucinous breast cancer - a rare type of breast cancer - including its symptoms, diagnosis, treatment and how to get support.

1. What is mucinous breast cancer?

Mucinous breast cancer is a rare type of breast cancer. It gets its name because the cancer cells are surrounded by a substance called mucin. 

Mucinous breast cancer is a type of invasive breast cancer. This means it has the potential to spread from the breast to other parts of the body. 

It’s sometimes found alongside another type of breast cancer called invasive breast cancer (no special type). This may be referred to as ‘mixed’ mucinous breast cancer. 

Mucinous breast cancer found on its own, known as ‘pure’ mucinous, is less common. Pure mucinous breast cancer generally has a better prognosis (outlook) than most other types of invasive breast cancer.

Mucinous breast cancer can occur at any age but is more commonly found in women over 60.

2. Symptoms of mucinous breast cancer

As with most types of breast cancer, the symptoms of mucinous breast cancer include:

  • A lump or thickening of the breast tissue
  • A change of skin texture such as puckering or dimpling of the skin
  • A lump or swelling under the arm
  • Changes to the nipple
  • Discharge from the nipple
  • A change in the size or shape of the breast

Routine breast screening can often pick up cancer before a woman notices any symptoms. Therefore, some women will be diagnosed with mucinous breast cancer after attending breast screening without having any of the symptoms above.

3. Diagnosing mucinous breast cancer

Mucinous breast cancer is diagnosed using a range of tests. These may include:

  • A
  • An ultrasound scan (using sound waves to produce an image)
  • A core biopsy of the breast and sometimes lymph nodes (using a hollow needle to take a sample of breast tissue to be looked at under a microscope – several tissue samples may be taken at the same time)
  • A fine needle aspiration (FNA) of the breast and sometimes lymph nodes (using a fine needle and syringe to take a sample of cells to be looked at under a microscope)

4. Treatment for mucinous breast cancer

As with all types of breast cancer, the treatments you’re offered will depend on the features of the mucinous breast cancer (such as sizegradehormone receptor status and HER2 status).

Treatment aims to remove the cancer and reduce the risk of it coming back or spreading to other parts of the body.


Surgery is usually the first treatment for mucinous breast cancer.  

There are two main types of surgery:

  1. Breast-conserving surgery, also known as wide local excision or lumpectomy – removal of the cancer with a margin (border) of normal breast tissue around it
  2. Mastectomy – removal of all the breast tissue, usually including the nipple area

The type of surgery recommended depends on:

  • Where the cancer is in the breast
  • The size of the cancer relative to the size of the breast
  • Whether more than one area in the breast is affected

Sometimes more surgery is needed if the margin of normal tissue surrounding the cancer that was removed during the first operation is not clear. This is to ensure all the cancer has been removed. In some cases, this second operation will be a mastectomy.

Most women who have a mastectomy will have the option to have breast reconstruction.

Some women decide not to have, or are unable to have, breast reconstruction. If you have a mastectomy and don’t have reconstruction you can wear an artificial breast form (prosthesis) inside your bra to restore your shape. Find out more about breast protheses, bras and clothes after surgery.

Some women choose not to have reconstruction or wear a prosthesis.

Surgery to the lymph nodes

Your treatment team will want to check if any of the lymph nodes (glands) under the arm contain cancer cells. This, along with other information about your breast cancer, helps them decide whether you will benefit from any additional treatment after surgery.

Mucinous breast cancer is less likely to spread to the lymph nodes than most other types of breast cancer. This is particularly the case if the cancer is small or if it’s pure mucinous breast cancer. 

Find out more about surgery to the lymph nodes.

Adjuvant (additional) treatments

After surgery you may need further treatment. This is called adjuvant treatment and can include:

The aim of this treatment is to reduce the risk of breast cancer returning in the same breast, or spreading elsewhere in the body. 

Which treatments are recommended will depend on your individual situation.  

Some of these treatments are given before surgery. This is known as neo-adjuvant or primary treatment.   

5. After treatment

You will continue to be monitored after your hospital-based treatments (such as surgery, chemotherapy or radiotherapy) finish. This is known as follow-up

It can be difficult to know how your breast or scar should feel. The area around the scar may feel lumpy, numb or sensitive. This means that you'll need to get to know how it looks and feels so you know what is normal for you. This will help you to feel more confident about noticing changes and reporting them early to your GP or breast care nurse.

Having breast cancer in one breast means the risk of developing cancer in the other breast (a new primary breast cancer) is slightly higher than in someone who's never had breast cancer. Therefore it's important to be aware of any new changes to your breasts and to report these as soon as possible.

6. Coping with a diagnosis of mucinous breast cancer

Being diagnosed with breast cancer can be a difficult and frightening time. 

If you’d like any further information and support or just want to talk things through, speak to one of our experts by calling our free helpline - please see further below.

Many people find it helps to talk to someone who has been through the same experience as them. Our Someone Like Me service can put you in touch with someone who has had a diagnosis of breast cancer, so you can talk through your worries and share experiences over the phone or by email - please see further below.

You can also visit our online forum and join one of the ongoing discussions.

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Quality assurance

Last reviewed in August 2021. The next planned review begins in September 2023.

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