Breast cancer is diagnosed on routine screening procedures or after detection of symptoms. For example, women who notice nipple changes or changes in their breast or feel a lump in their breast may consult their physicians who may follow up the lesion to diagnose the tumor as cancerous or non-cancerous.

Diagnosis of breast cancer involves:

Examination of the breast and surrounding lymph nodes

Both breasts, nipples and lymph node in the armpits, under the collar bone and neck are examined. The lump or skin changes are noted. If the lump appears to be fixed to the skin over it or tissues and chest wall under it, it is most likely to be cancerous.

Mammogram

A mammogram is an X ray of the breast. Mammograms are routinely employed to screen women over 50 for breast lumps and cancer.

Breast ultrasound

Women under 35 need breast ultrasound scan only. This is because younger women have denser breasts, which means a mammogram is not as effective as ultrasound in detecting cancer. Ultrasound uses high-frequency sound waves to produce an image of the inside of the breast tissues. An ultrasound also helps to detect if the breast lump contains solid cells or liquid like mucous.

Biopsy

This involves taking a sample of tissue cells from the breast tissues or breast lump and examining them under the microscope to see if they are cancerous. Breast biopsy may be of more than one type. Initially a small amount is taken from the lump using a fine needle. This is called FNAC or Fine needle aspiration cytology. Needle biopsy is the most common type of biopsy. If the lump is not clearly defined imaging studies like ultrasound or X-ray but sometimes MRI may be used to guide the needle for the biopsy. Larger amounts of tissues can be taken for biopsy using core biopsy or excisional tissue biopsy. Samples or whole of lymph nodes from the armpits may also be taken as biopsy to detect spread to the lymph nodes. A biopsy of the tumor is the surest way of diagnosing the type and grade of breast cancer.

Computerized tomography scan (CT scan), Magnetic Resonance imaging (MRI), X rays and liver ultrasound for metastasis

These are needed to check whether the cancer has spread to the lungs or liver. An MRI scan of the breast may be needed to clarify or to assess the extent of disease within the breast. A bone scan may be recommended to check if the cancer has spread to the bones. Similarly blood tests are recommended to check for adequate functioning or involvement of the liver and kidneys as well.

Hormone receptor test

This is a test that determines the specific types of treatment that will be useful for a patient. Breast cancer cells can be stimulated to grow by female hormones like estrogen and progesterone in some women who have estrogen receptors (ER) or progesterone receptors (PR) on their tumor. These women respond to therapies that stop the effects of the hormones or by lowering the level of these hormones. This is known as hormone therapy.

HER2/neu protein test

While in some women hormones can encourage the growth of some breast cancers, other types are stimulated by a protein called human epidermal growth factor receptor 2 (HER2). These types of cancer may be treated using drugs to block the effects of HER2. This type of targeted therapy is called biological therapy.

Staging of breast cancer

Once the cancer is diagnosed, it is divided as per the histological or cellular type. Next the cancer is staged. Early detection means an early stage of cancer that is usually amenable to treatment.  Late stage cancers are usually advanced and have already spread to vital organs and may mean a shortened lifespan and non-responsiveness to therapy.

A simplified version of staging is:

• Sometimes, ductal carcinoma in situ (DCIS) is described as Stage 0.
• Stage 1 indicates that the tumour measures less than 2cm and the lymph nodes in the armpit are not affected.
• In stage 2 the tumour measures between 2cm and 5cm or the lymph nodes in the armpit are affected, or both.
• In stage 3 the tumour measures between 2cm and 5cm and may be attached to structures in the breast, such as skin or surrounding tissues. The lymph nodes in the armpit are affected.
• In stage 4 the tumour is of any size and the cancer has spread to other parts of the body.

Grading of the cancer

The cancer is graded as well. A ''well-differentiated'' tumor for example is low grade and resembles normal tissue. A ''poorly differentiated'' tumor is composed of disorganized cells and, therefore, does not look like normal tissue and is termed high grade. Some are ''moderately differentiated'' or intermediate grade.

The TNM staging system may also be used to describe breast cancer. It can provide accurate information about the diagnosis. T describes the size of the tumour, N describes whether cancer has spread to the lymph nodes and M gives an indication of whether the cancer has spread to other parts of the body.