Breast cancer is one of the most common cancers in women, and, although new treatments are improving the outlook for those who develop the disease, the best hope lies in early detection and treatment.

We all know about examining our own breasts regularly, but what about mammograms? What are they? Who should have them, and how regularly?

What are mammograms?

A mammogram is a special type of breast x-ray. Although these have been available since 1969, they have changed a lot, even in the last decade. Modern techniques use dedicated equipment, used only for breast X-rays, which produce a high-quality film, using the minimum amount of radiation.

If you were to start having mammograms every year at the age of 40, and continue this until you were 90, you would receive 10 rads of radiation. If you had to be treated for breast cancer, you would receive several thousand rads.

During a mammogram, the breast is compressed, which spreads the tissue apart, allowing a lower dose of x-rays to be used. This may be a bit uncomfortable, but is necessary to produce a good result. The compression is only for a few seconds of the examination, and the entire procedure takes about 20 minutes. You will have two views taken for a screening mammogram.

This produces a black and white image of the breast tissue on a large sheet of film, which is then interpreted by a specialist radiologist.

This can be difficult since there is a wide range of what is considered normal. What is normal also varies from woman to woman, so sequential mammograms can help in diagnosis, since subtle changes will be easier to see if previous films are compared.

A common abnormality is calcifications, divided into macro- and micro-calcifications. These are tiny mineral deposits in the breast tissue, which appear as white spots on the film. Large deposits, macro-calcifications, are not usually associated with cancer, and result from changes in the breast with age, or old injuries or inflammation. They are present in 50 percent of women over the age of 50.

Smaller calcifications, or micro-calcifications, do not always mean that cancer is present, and some will not even be biopsied, but re-examined regularly.

A mass can also be seen on mammograms. These can be due to many things other than cancer, including cysts. The appearance of some masses may mean that you will have a biopsy immediately, while others will simply be watched for a while.

Mammography cannot prove that an abnormal area is cancer. If there is a suspicion of cancer, then the suspicious tissue will be removed (biopsied), and looked at under a microscope to tell if it is cancer.

The biopsy can be done using a fine needle, or the lump can be removed surgically.

Who should have a mammogram?

There is no simple answer to this question! Breast cancer takes years to develop, and early in the disease, there are no symptoms. If breast cancer is detected before there is any spread to the local lymph glands, then survival after treatment is 97 percent.

If the cancer has spread to the lymph glands under the arms, the survival drops to 76 percent. If there is distant spread, to other organs, then survival drops to 20 percent.

The earlier it is detected the better the chances of successful treatment.

The goal of screening mammography is to detect cancer when it is still too small to be detected by you or your doctor on examination.

In America women are advised to have screening mammography every year once they reach 40. The American Cancer Society has based their decision on the fact that one in 66 women in their 40s will develop breast cancer.

Results from some studies have suggested that there are between 17 and 44 percent fewer deaths from breast cancer among women in their 40s who have had mammography.

Breast cancers found by mammography in women in their 40s are smaller and at an earlier stage, than cancers found in women who did not have regular mammography.

There is at least one South African medical aid group who reward women for having an annual mammogram after the age of 45.

However, the American guidelines are not followed everywhere, and other studies have not demonstrated the same benefits as those quoted by the American Cancer Society.

In your 40s your breasts are usually still very dense, so mammograms will be more difficult to interpret. As you get older, the density of your breast tissue decreases, particularly if you elect not to take hormone replacement therapy (HRT), after the menopause, making it easier to detect cancer on mammogram.

At the end of the day

In a country like South Africa, which has many other health problems to deal with, there is no consensus statement issued about mammography for breast cancer, and so women are left to make up their own minds. At the end of the day, one of the things which will probably make your mind up for you, is whether your medical aid will pay for routine mammography.

The situation changes if you are at high risk for breast cancer. If you have a strong family history of breast cancer, then you must discuss your options with your own doctor, who may well recommend regular mammograms at an earlier age.

Mammograms cannot detect 100 percent of breast cancers, so screening must consist of a combination of regular self-examination, by yourself, and your doctor or clinic nurse, and mammograms where appropriate.

Discuss whether or not to have regular mammograms with your own doctor.