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1. What is mucinous breast cancer?
2. Symptoms 
3. How it’s diagnosed 
4. Treating mucinous breast cancer 
5. After treatment 
6. Further 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 ductal breast cancer. 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 

Possible 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
  • constant pain in the breast or armpit

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. How it’s diagnosed 

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

  • a mammogram (breast x-ray)
  • 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)
  • 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. Treating mucinous breast cancer 


Surgery to remove the cancer is usually the first treatment for mucinous breast cancer.  

The type of surgery recommended may be:

  • breast-conserving surgery: removal of the cancer with a margin (border) of normal breast tissue around it, also called wide local excision or lumpectomy
  • a mastectomy: removal of all the breast tissue including the nipple area

If you’re going to have a mastectomy, you’ll usually be offered breast reconstruction.

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 (glands) under the arm 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 on our surgery page. 

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 developing in the other 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

6. Further support 

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

Many people find it helps to talk to someone who has been through the same experience as them. Breast Cancer Now’s 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. You can also visit our online Forum and join one of the ongoing discussions. 

If you would like any further information and support about breast cancer or just want to talk things through, you can speak to one of our experts by calling our free Helpline on 0808 800 6000.

Last reviewed: December 2018
Next planned review begins 2020

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