Invasive lobular breast cancer

The information on this page will help you understand more about invasive lobular breast cancer. We recommend that you read it along with our booklet Understanding Cancer of the Breast, which you can download here (pdf, 2.6MB).

What is invasive lobular breast cancer?

Breast tissue is made up of milk lobules and milk ducts where milk is made and carried to the nipple during breastfeeding. Invasive lobular breast cancer happens when cancer cells start to grow within the lobules and spread into the surrounding tissue.

How common is invasive lobular breast cancer?

Invasive lobular breast cancer is uncommon, affecting about 10–15 per cent of all women with breast cancer. It can occur at any age, but more commonly affects women in the 45-55 year age group. Men can also get invasive lobular breast cancer but this is very rare. Someone who has invasive lobular breast cancer in one breast has a slightly greater risk of it occurring in the opposite breast at a later date. It is sometimes found in both breasts at the same time.

What are the symptoms?

Unlike other forms of breast cancer, invasive lobular cancer is more likely to show up as a thickening of the breast tissue rather than a definite hard lump. Because the symptoms can be vague, these cancers may sometimes grow to a larger size than other breast cancers before they are picked up.

How is a diagnosis made?

Once you have seen your GP (family doctor), you will be referred to a specialist breast unit where you will be seen by a doctor or specialist nurse. Following a physical examination of your breasts, you may have other tests such as:

  • A mammogram, which is an X-ray of the breast.
  • An ultrasound, which is a picture of the breast using sound waves.
  • A core biopsy, where a small piece of tissue is removed under a local anaesthetic and looked at under the microscope.

You may also have further tests to check that the cancer has not spread to other parts of your body.  

Invasive lobular breast cancer can sometimes be difficult to diagnose. It is less likely to show up as a firm lump and is therefore not as easy to feel. It is also more difficult to see on a mammogram. Click here for more information on the diagnosis of breast cancer.

What treatment will I be offered?

Your doctor will discuss which treatments may be best for you. The treatments you are offered will depend on many factors, including the size and stage of the cancer.


As with most types of breast cancer, surgery is usually the first treatment. This can be a wide local excision (removal of the cancer and an area of normal tissue around it) or a mastectomy (removal of the whole breast). You may be given a choice between these two types of surgery.

If a wide local excision is possible for you, there is a chance that you may need a second operation to make sure that the cancer has been completely removed. In some cases, it may be necessary to remove the whole breast.

Invasive lobular cancer can sometimes affect more than one area in the breast. If this is the case, your surgeon may advise you to have a mastectomy. A sentinel lymph node biopsy is usually done at the time of surgery to find out if the cancer has spread to the lymph nodes in the axilla (glands in your armpit). Click here for more information on sentinel lymph node biopsies and surgery for breast cancer.

Adjuvant treatment

Adjuvant treatment is treatment given in addition to surgery and includes radiotherapy, chemotherapy, and hormone therapy. The aim of adjuvant treatment is to reduce the risk of the cancer coming back in the same breast (local recurrence), the opposite breast or elsewhere in the body.

If you have a wide local excision, you will usually be offered radiotherapy to reduce the risk of the cancer coming back in the same breast. If you have a mastectomy, you may also need radiotherapy. For more information on radiotherapy, see our factsheet on radiotherapy and breast cancer (pdf, 292KB).


You may also be advised to have chemotherapy. Click here for more information on chemotherapy and breast cancer.

Hormone therapy

If your tumour is oestrogen receptor positive, you may be offered hormone therapy. This means that your tumour depends on the hormone oestrogen for growth. Hormone therapies work in different ways to block the effect of hormones on cancer cells. Commonly used hormone therapies include:

  • Tamoxifen
  • Anastrozole (Arimidex®)
  • Letrozole (Femara®)
  • Exemestane (Aromasin®)
  • Goserelin (Zoladex®)

These therapies are all taken as tablets over several years with the exception of Goserelin, which is an injection. Your doctor will discuss with you which drug is best for you.

Biological Therapies

Biological therapies work by blocking the growth and spread of cancer by changing the biology of cancer cells. The most well-known biological therapy is a drug called Trastuzumab (Herceptin®). Trastuzumab is only suitable if your cancer has high levels of HER2, a protein that encourages cancer cell growth.

Most invasive lobular cancers are oestrogen receptor positive. For more information call the National Cancer Helpline on Freefone 1800 200 700 and speak with a specialist cancer nurse in confidence.

What if my cancer has spread to another part of my body?

If your cancer has spread to another part of your body, this is called advanced or secondary breast cancer. You will be offered treatment to help control the disease. Your doctor may offer chemotherapy, hormone therapy, biological therapies or a combination of these treatments. Click here for more information on secondary breast cancer.

Coping with breast cancer

Being diagnosed with invasive lobular breast cancer can be an anxious and frightening time. But everyone responds differently to their diagnosis and has their own way of coping. It is important that you feel able to talk to your specialist or breast care nurse about any questions or concerns you may have.

You may feel alone, particularly as invasive lobular breast cancer is uncommon. Remember that there are people who can support you, so don’t be afraid to ask for help.

You can let other people know how you are feeling, including your family and friends, so that they can be more supportive. It can also help to discuss your feelings or worries with your breast care nurse or your specialist. Alternatively, a counsellor or psychotherapist might be more appropriate if you want to talk through your feelings in more depth over a period of time. Your breast care nurse, specialist or GP can usually arrange this.

Click here for more information on coping and how the Irish Cancer Society can help you.

Call our National Cancer Helpline

Freephone 1800 200 700 to talk to a specialist cancer nurse.
It's open Monday-Thursday from 9am to 6pm and Friday from 9am to 5pm
Date Last Reviewed: 
Thursday, June 11, 2015
Date Last Revised: 
Thursday, June 11, 2015