What are the types of breast cancer?

Non-invasive breast cancer

DCIS (Ductal Carcinoma In Situ)

DCIS is a condition in which there are cancer cells present within the milk ducts of the breast, but they are confined to the duct by a protective layer. Over time, these cancer cells may break through this layer into the surrounding breast tissue and become an invasive cancer. As we cannot accurately predict when or if this will happen, DCIS is currently always treated by surgical excision and radiotherapy may be recommended.

LCIS (Lobular Carcinoma In Situ)

Even though the name suggests that this is a similar condition to DCIS, it is not considered to be a precursor to invasive breast cancer, but more of a risk factor for developing breast cancer in the future. If a needle biopsy reveals LCIS, generally a surgical (open) breast biopsy will be performed to rule out any surrounding malignant (cancerous) changes. Given the higher risk of breast cancer, Dr Bell will discuss a tailored screening program with you.

Invasive breast cancer (carcinoma)

Invasive carcinoma, no specific type (NST)

This is by far the most common type of breast cancer, accounting for 70-80% of all invasive breast cancers. It is also known as invasive ductal cancer (IDC) and arises from the ducts of the breast.

Invasive lobular carcinoma (ILC)

ILC is the 2nd most common breast cancer type, accounting for 10% of cases. It arises from the lobules of the breast and can have microscopic extensions which may not be visible on conventional breast imaging. Generally, Dr Bell will order an MRI scan to further delineate the size of the cancer. Lobular cancers also have a slightly higher chance to affects both breasts (bilateral cancer).

Other types

A number of other types of breast cancer account for the remaining invasive breast cancers. These include tubular carcinoma, mucinous carcinoma, medullary carcinoma, metaplastic carcinoma and others.

Other specific cancers

Inflammatory breast cancer

This is a specific type of breast cancer that presents with a red or inflamed-looking breast with possible skin dimpling or pitting. The breast may feel swollen and enlarged. This type of cancer behaves more aggressively, but fortunately is quite rare. Generally, chemotherapy will be the first line of treatment, followed by surgery.

Paget’s disease of the nipple

This is a rare presentation of breast cancer in which skin changes appear on the nipple and surrounding tissue (areola). These changes may involve crusting and an eczematous appearance. This condition is often associated with underlying DCIS and/or invasive cancer.

Malignant phyllodes tumour

Amongst phyllodes tumours, malignant phyllodes tumours are the least common variant. These tumours arise from the stromal cells of the breast and have a leaf-like pattern. Treatment generally includes surgery and radiotherapy.

Receptor status

Each breast cancer will be tested for the absence or presence of 3 receptors:

• 2 hormone receptors

  • Oestrogen (ER) and Progesterone (PR) receptors

• Overexpression of HER-2 receptors

Breast cancers can be characterised into different subtypes by whether or not they are ER, PR and HER-2 positive and this greatly influences management. For example, breast cancer patients who have ER/PR positive tumours may be recommended hormonal treatment as part of their management. Dr Bell will be able to discuss the receptor status of your cancer with you, as well as the likely implications for your treatment.

Size of the cancer

Usually, breast imaging will give an indication of the size of the tumour. However, the final measurement will be on the pathology report, available after surgery.

Grade of the cancer

Breast cancer are graded into 3 grades

• Grade 1 (low grade/well differentiated) – usually slow growing

• Grade 2 (intermediate grade/ moderately differentiated) – intermediate growth

• Grade 3 (high grade/poorly differentiated) – faster growing

Stage of the cancer

The extent or stage of breast cancer is based on the TNM (Tumour, Nodal and Metastases) system used by the AJCC (American Joint Committee on Cancer). This is an internationally accepted system to determine the stage of a variety of cancers.

Each component (T for primary breast tumour, N for lymph node status and M for distant metastases) receives a score that describes the size and extent of the cancer. Based on this score, the final stage of the cancer is calculated. The final stage ranges from stage 0 (non-invasive cancer) to stage IV (metastatic cancer).