This is simply a special type of x-ray of the breasts.

It has three main indications:

• to show the features of the breast lump (is it cancer?)

• to show if there are any other concerning features in the breast that the patient or the doctor cannot feel, this is called searching for an impalpable lesion

• to screen for breast cancer (population screening to detect early breast cancer before a lump becomes palpable).

Method

Two compression (breast flattening) views of each breast are taken. It is a relatively safe investigation, as the amount of irradiation to the patient is minimal (less than 0.2 cGy of radiation). A ballpark figure of risk of actually getting a f/f ""11 new breast cancer as a result of this irradiation is one breast cancer per one million mammograms per year, with a latent period of ten years or more for the cancer to become evident. This shows that mammography is really quite a safe procedure and the benefit far outweighs the risk. We are exposed to more radiation in our environment than with mammography.

The accuracy of mammography increases with age, and we do not do this procedure in women under thirty-five years unless for specific indications. In young women, the breasts are dense, due to the presence of florid glandular tissue and ducts. After forty years, the breast glands and ducts are replaced by fat, which is radiolucent and thus promotes satisfactory mammography. This means that cancers are easier to detect in fatty breasts, using mammography.

The features of breast cancer on a mammogram are:

• Dense rounded mass with radiating spicules (small spikes); benign condition called a radial scar can also give this appearance, and biopsy is mandatory to differentiate these two conditions

• Small regions of calcification (micro calcification)

• Areas of linear (line) or punctuate (point) calcification

• Distortion of the breast architecture.

The mammogram apparatus (machinery) must be of excellent quality, to help the doctor make the correct assessment. The radiologist needs the best available equipment, including high quality x-ray films. It is Important to look for a centre, which specializes in mammography when choosing a place to go for this investigation.

Screening

Screening mammography is recommended annually for all women of forty years and older. Screening will pick up the impalpable breast cancer. It has been shown in extensive studies in the United Kingdom, the USA, Europe and Canada, that regular screening reduces mortality from breast cancer by about 20%. This is a very significant figure and it supports this approach. Many recent reports have looked at the negative impact of mammography and questioned whether it alters survival.

There is an enormous body of consistent evidence on the relationship between tumour size, disease stage, and survival. As tumours increase in size the likelihood of nodal involvement and distant metastases increases, which is associated with a poorer prognosis. Strong evidence suggests that tumours detected on mammography are smaller in size than palpable tumours.

Poor quality of mammography can result in a decrease in identifying tumours and result in the implication that mammography misses breast cancers. These small mammographically detecting Cancers may be treated with breast conserving surgery or mastectomy with immediate reconstruction. Screening requires both a clinical examination by a physician and mammography. In a country with limited resources like South Africa, free screening for all women is not yet possible or cost effective. The more people who go for screening mammography, the cheaper it is to run mammogram units.

Under ideal circumstances, annual screening for all women over fifty is recommended and a baseline mammogram between 35 and 40 followed by a mammogram screening every year or two for women between forty and fifty years is recommended. In those women with a family history of breast cancer screening should start 10 years before the youngest relative developed a breast cancer.

Ultrasound (sonar) of the breast

A7.5 megahertz linear array transducer is the apparatus used to obtain a real-time ultrasound of the breast. It is ideal to differentiate solid from cystic masses and is the best modality to detect breast cysts.

Ultrasound, which works like a TV viewing the findings on a screen, is the investigation of choice for women less than thirty-five years of age and for pregnant and lactating women due to the density of the breast.

The appearance of a cyst is of a well defined, round, echo free, small ball, with posterior enhancement. A solid lump is full of echoes and demonstrates no posterior enhancement. These cysts are simply pockets of liquid or fluid, that cause breast lumps, which may be quite painful. Ultrasound is also an excellent investigation for assessing whether lymph nodes are benign or malignant, enabling the doctor to decide whether the patient should start with chemotherapy.

Sonar cannot detect calcification. Micro calcification, whether from a cancer or a benign lump, will not be picked up with ultrasound. It will be detected by mammogram.

Magnetic resonance Imaging ('MRI')

This should not be used as an initial radiological assessment for the breast, as it is a very sensitive investigation (i.e. it may "over read" potential breast problems). But in patients with recurrent breast disease (lumps) after surgery or radiotherapy (DXT), where the breast is filled with fibrosis, in women with strong family histories, women with lobular carcinoma, or those who have had primary chemotherapy, MRI may be more reliable than either mammography or ultrasound. It is being used more frequently to assess breast disease today. The major disadvantage is its expense and that a special breast coil is needed for the machine. MRI is offered in certain centres in this country and is a useful tool to aid the specialist radiologist in assessing the breast. MRI is the best investigation today, to detect a leak from a silicone breast prosthesis that has ruptured.