Breast cancer health centre

Invasive breast cancer

Invasive breast cancer is the most common type of breast cancer in both women and men and accounts for about 90% of all breast cancers.

What is invasive breast cancer?

Invasive breast cancer has a number of different names. It may also be referred to as invasive breast cancer of no special type (NST), breast cancer not otherwise specified (NOS) or invasive ductal carcinoma of the breast (IDC).

It begins in the lining cells of the breast but it doesn't necessarily stay there. Instead it can grow through the milk duct walls and into the surrounding breast tissue - and it can metastasise, which means it can spread to other areas of your body.

How is invasive breast cancer diagnosed?

Invasive breast cancer may cause a hard, immovable lump with irregular edges to form in your breast. That lump can be felt during a breast examination. In some cases the cancer causes the nipple to become inverted. A mammogram may show areas of calcification where calcium has collected in old cancer cells.

If your physical examination and mammogram indicate you may have invasive breast cancer, your doctor may arrange a biopsy to obtain cells for analysis. The results of this test will help confirm your diagnosis. They will also help determine what treatment will be most effective for you.

Since invasive breast cancer often spreads, your doctor may recommend additional tests to look for cancer cells in other areas of your body. These tests could include:

• CT scan
• MRI
• PET scan
• Bone scan
• Chest X-ray
• Axillary lymph node dissection (surgery to check the lymph nodes in the armpits for cancer)

Using the results from these tests, your doctor will be able to determine the stage of your breast cancer. The stage will help guide your treatment.

How is invasive breast cancer treated?

Most women with invasive breast cancer have surgery to remove the cancer. In 7 out of 10 cases breast-conserving lumpectomies - instead of mastectomies - are an effective treatment option. This will depend upon the size of your tumour and the extent of its spread throughout your breast and the surrounding lymph nodes.

In addition to surgery most doctors will recommend treating invasive breast cancer with chemotherapy, radiotherapy, hormone therapy, biological therapy or a combination of some of these treatments. Chemotherapy is a systemic treatment. It will target cancer cells throughout your entire body. Radiotherapy specifically focuses on the area around your breast cancer.