Breast cancer

Definition

Cancer of the breast tissue. Go figure...

Epidemiology

Commonest cancer in women - 1 in 3 malignancies in women are of the breast. 11000 women died of breast cancer in 2005 (and 81 men). Basically, there's lots of breast cancer so it's pretty important.

Pathophysiology

There are essentially two places breast cancer can arise from:

• ductal carcinoma - this effects the epithelial lining of the ducts. Hence, ductal. Cancer people are pretty good at naming stuff.
• lobular carcinoma - the effects the epithelial lining of the terminal ducts and lobules (found at the end of the ducts. It's where the milk is made).

Risk Factors

• Age
• FHx - sister or mother who has/had disease
• High premenopauseal insulin-like growth factor
• Born in North America/northern Europe

These are the four most important but there are others factors which affect risk:

• BRCA1, BRCA2 and TP53 gene predispose to cancer.
• Nulliparity
• Early menarche (before 11) or late menopause (after 55)
• HRT, oral contraceptives (due to oestrogen)
• Obesity after menopause
• FHx - first-degree relative who has/had disease
• Alcohol, diet with high saturated fats
• Radiation to chest

Clinical Features

The most important feature is a lump in the breast and 1 in 8 with a painless breast lump (90% of cancers are painless) will turn out to have breast cancer. Other features include:

• lumps under the arm
• retraction/inversion of the nipple
• bloody discharge from the nipple (intraduct carcinoma)

Other questions to ask in the history are: when the lump started; any change in size; menstrual history; any changes in the menstrual cycle; and family history.

On examination the key is to try and differentiate between breast cancer and benign breast disease. A hard, painless lump; irregular margins; fixation to chest wall; skin dimpling; unilateral discharge (with blood); anything else mentioned above: are all signs of breast cancer.

If these things aren't present or the opposite is true (e.g. regular rather irregular) are suggestive of benign breast disease.

Investigations

Screening

In 1987, the NHS started the National Health Service Breast Screening Programme (NHSBSP - I thought I'd put it in so if you see it, you know what it means). This screening is done by mammography which is offered between the ages of 50 and 70 and it should be done every 3 years. It has been shown to significantly reduce the mortality rates in 55-69 year olds.

Further investigations

This is a breast. If you feel you haven't seen enough breasts, a visit to any reputable pornography website should give you plenty of "experience"

There are loads of investigations that can be done for breast cancer. Let's start with the important first-line ones:

• Mammography - essentially, a breast X-ray which can quite painful as the picture on the right shows. It is good for less dense breast tissue i.e. older breast, particularly after the menopause. This is why the screening programme isn't as effective in younger women an is thus limited to 50-70 year olds.
• Ultrasound Scan (USS) - this is good for denser breast tissue i.e. what is generally found in young women. Often, it is more diagnostically useful than mammography.

Other imaging scans include (these are not, however, done routinely but with specific indications): chest X-ray; CT - abnormal CXR, neuro symptoms hepatosplenomegaly, lymphadenopathy, abnormal LFTs; bone scans - bone pain, distant mets, lymph mets, advanced disease; MRI - can be used in difficult cases (high false positives rate); and PET - distant mets.

The main three blood tests are to do with receptor status. Oestrogen receptor (ER), progesterone receptor (PR) and HER2 status are detected by monoclonal antibody techniques. These are done because they have implications for management.

Diagnostic procedures

• Core-needle biopsy - essentially, they use a hollow (hence, "core") needle and insert it into the mass and take a biopsy. With a palpable mass, this is done without the aid of imaging. If the mass is non-palpable, it is done by ultrasound or stereotactic mammography (two x-rays giving an exact location of the mass).
• Fine-needle aspiration (FNA) - this is a finer needle than the core-needle and is used for smaller lesions and palpable lesions. It has a high false-negative rate but low false-positive rate.

Excision biopsy removes the whole lesion. Incisional biopsy removes part of the lesion and is used in large lesions. Open biopsy uses a radio-opaque needle, can be done under local anaesthetic and has few false negatives (used in non-palpable masses).