AU-KBC  RESEARCH CENTRE

Introduction
Breast cancer is the second most common malignancy affecting women worldwide. The interaction between genes and environment plays an important role in cancer predisposition. Breast cancer results mainly from hereditary and non-hereditary factors .

  • Hereditary breast cancer occur due to mutations in high penetrant genes such as BRCA1 and BRCA2.
  • The non-hereditary forms of breast cancer are the 'sporadic' cases due to mutations in a large number of low penetrant variants. A small number of syndromes also manifests such forms of breast cancer.

A strong family history, early puberty and late menopause are the major risk factors for breast cancer in women. Clinical examination, mammography and biopsy are a few of the techniques used to diagnose breast cancer.  Standard treatment options include local therapy like surgery or radiation therapy and systemic therapy like chemotherapy, biological therapy and hormone therapy. Cancer gene therapy is now emerging as a therapeutic approach for correcting defects at the gene level.

Understanding Breast cancer

Under normal conditions, cells divide for various reasons such as replacement of aging tissue, increased metabolic demands etc. However, when cell division is unchecked, the result is disastrous leading to the development of cancer. Cancer may thus be defined as an abnormal proliferation of cells, which results from uncontrolled cell division. The three general mechanisms by which cancer can occur are

Breast cancer is trigerred by any one of these processes. To understand the disease process in detail, a brief knowledge of the breast morphology is essential.

Breast tissue is broadly divided into two regions:
a. Glandular region
b. Fatty region

Source-American Cancer Society

Glandular region is composed of structures called 'lobules' and these lobules connect to the nipple via tube like structures called 'ducts'. It is also called as milk passage of the breast. Hence, breast cancer is called as lobular carcinoma if the malignant cells arise from the lobules, and ductal carcinoma if it arises from the ducts.

Breast cancers are also divided into in situ (benign) and invasive carcinomas. In situ means in place (i.e.) the tumor cells stay within the breast tissue and do not spread, whereas invasive carcinoma results in metastasis (spread of the tumor). When cancer cells spread, they either enter the blood stream or the lymphatic channel.

Benign breast lumps may occur due to fibrocystic changes in the breast where a scar like tissue holding a sac of fluid can cause pain in the breast. They are also called as fibroadenoma.

Invasive carcinoma is quite dangerous as it not only affects the primary organ, but the cancerous cells target the other vital organs in the body. The common types of invasive breast cancer are

  • Invasive Ductal Carcinoma
  • Invasive Lobular Carcinoma.
The other rare types of cancer are
  • Medullary Carcinoma
  • Colloid Carcinoma
  • Adenoid Cystic Carcinoma
  • Tubular Carcinoma
  • Paget's disease of the breast

Medullary Carcinoma:

It is an invasive carcinoma with distinguished features like large cancer cells and immune cells at the border of the tumour tissue. It also has a clearcut margin between tumour tissue and the normal tissue. It accounts for 5% of all cancers and has a better prognosis than invasive lobular and ductal cancer.

Colloid Carcinoma:

This type is produced by mucous producing cancer cells of the body and hence it is also known as mucinoid carcinoma. This cancer has a better prognosis than other types of invasive cancer.

Adenoid Cystic Carcinoma:

This is a very rare type of cancer arising from salivary glands.

Paget's disease of the breast:

This disease starts with scaly rashes in the nipple or around the dark regions surrouding the nipple (areola). When these cells are viewed under the microscope, the red scaly cells appear as arising from intra epithelial extension of underlying invasive or in situ ductal carcinoma. The cause for this disease is unknown and is often confused with other skin conditions like eczema, dermatitis and psoriasis.

The common type of cancer seen in many of the breast cancer patients is the ductal carcinoma (both in situ and invasive).

A complete atlas of the pictures of various types of breast cancer are shown in this web page

Breast cancer affects both the sexes but women face a higher risk of developing it. The probable reasons could be estrogens, which play a very important role in cell differentiation of breast tissue.

Breast Cancer Stages

Breast cancer is divided into four stages according to size.

Stage 1 - Tumour is small in size, less than 2cm in diameter and there is no involvement of lymph nodes .
Stage 2 - Size of the tumour increases up to 5cm with or without the involvement of lymphnodes.
Stage 3 - Tumour cells spread to axillary lymphnodes but not to other parts of the body.
Stage 4 - The cancer cells spread to other parts of the body.

The staging of breast cancer is important because the diagnosis, disease prognosis and treatment options will differ accordingly. Normally, patients in stage 1 & 2 have better prognosis than those in stage 4.

The American Joint Committee on Cancer (AJCC) has staged breast cancer based on tumour size, lymph node status and metastasis.

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