Dr Danie Schneider
Obstetrician and Gynaecologist, Somerset West


What is a mammogram?

A mammogram is a breast X-ray used for breast cancer screening.  Breast cancer screening is a way doctors can check for early signs of breasts cancer in women who have no symptoms of breast cancer.

How is a mammogram done?

Before the mammogram is done, you will be asked to undress from the waist up and wear a hospital gown. A mammogram, including a tomogram, takes about 20 minutes from start to finish. During image acquisition, a female technician will place the breast between two plates. One of the plates takes an image of the breast, while the other holds the breast in place.

Gentle  compression of the breast is needed to allow the technician to get a clearer image, displaying all the breast tissue. It also keeps the breast stable during the test.

What is a tomogram?

It is important to understand that a mammogram is a 2 dimensional (2D) study.  A tomogram, also called a 3D-mammogram, was developed to overcome the biggest problem with mammograms which is the superimposition of breast tissue, where tissue can “overlap” and obscure underlying lesions. In a tomogram the x-ray tube moves in an arc over the breast to capture multiple images from different angles. Using computer software, multiple images are then reconstructed.

Research has shown that a tomogram has a lower false positive rate (better at ruling out cancers in healthy patients) and may detect more cancers. An important research study is in progress in the USA where researchers are evaluating the place of a tomogram in breast cancer screening.  The trail will help us move towards a more personalised approach which tailors mammography for each women based on her family history and individual risk.

How can I reduce discomfort during a mammogram?

If you still get a monthly period, try to avoid scheduling your mammogram just before or during your period, if possible, as the breasts are more sensitive at this time.

It is helpful to inform the technician about a previous history of painful mammograms or if you are known with dense breast tissue.

Some women have found that limiting caffeine intake for a week before the mammogram have decreased discomfort.

Taking a non-steroidal anti-inflammatory 60 minutes before the mammogram can be helpful.


Why should I consider going for a mammogram?

Breast cancer is the most frequent cause of cancer death in women worldwide. The goal of breast cancer screening is to detect breast cancer at an early stage, before a woman discovers a lump. Breast cancer is more easily treated and more likely to be cured when it is diagnosed early. A mammogram is the best screening test for picking up breast cancer early and reducing the risk of dying from breast cancer.


What are the risks?

There is no evidence that mammography itself is dangerous or can produce cancer. Studies show that the number of lives saved by finding breast cancer early greatly outweighs the very small risks that come from radiation exposure.

It is important to understand that screening for breast cancer can however potentially cause harm when false-positive results occur. This means the mammogram suggests a woman might have cancer when she does not. This can lead to more tests (including a biopsy which can be painful) and unnecessary worry. We know that false positive results are more likely to happen in women younger than 50 than they are in older women. Experience shows that approximately 10 percent of screening mammograms require additional evaluation and it is important to realise that the lesion turns out to be benign in more than 90 percent of these cases .

Sometimes, mammograms can find a type of cancer that would never have affected a woman’s health. This is called over diagnosis and can be a problem since treating these cancers does not have any benefit and can potentially cause harm. There is however no sure way to know which cancers found by screening will lead to problems and which won’t.

Some women have heightened anxiety about breast cancer and mammography for several months after a false-positive reading. It is important to discuss the above during your consultation before going for a mammogram.


What will happen after the mammogram?

A radiologist will review and interpret your mammogram. Remember to bring your previous mammogram along as every woman’s mammograms are unique. It increases the accuracy of your test significantly if the previous images are available for comparison.   The radiologist will discuss your results with you before you leave the X-ray department. Feel free to use this opportunity to ask questions pertaining to mammography and breast cancer screening. A report will be sent to our rooms and we will phone you within a few days. Please phone the rooms if you have any uncertainty or have not received feedback.

If your mammogram is reported as normal, further screening will be discussed at your next checkup. It is also important to remember that some breast cancers unfortunately cannot be seen on a mammogram. For this reason, while it is reassuring to get a normal test result, it’s important to schedule an appointment right away if you notice a lump in your breast or have any other concerns about your breasts.

It is good to be aware that a breast ultrasound is used in many cases as an additional examination to determine the nature of abnormalities detected on mammography or for added information in those women who have very dense breast tissue. This should be seen as a reassuring, additional test. The radiologist will make this decision on the day.

If your mammogram is reported as abnormal, you will likely need further testing. This can happen to about 1 in every 10 women and most often you  will need to have more images taken (either mammogram or ultrasound images). Needing more images is therefore common and does not usually mean that you have cancer. The extra images help the radiologist to have the most accurate and clear view of your breast tissue. Occasionally, additional testing such as a breast biopsy (where a small amount of tissue is removed for examination) is needed to follow up on an abnormal screening mammogram result. This we will usually arrange with a surgeon, but can be done by the radiologist under certain circumstances.


How will I know if I am at risk of breast cancer?

It is important to understand that the majority of women have an average risk/low risk (less than 15 percent lifetime risk) of developing breast cancer. In these women, age is the most important factor in your decision about when to be screened, because breast cancer incidence rises with age. Breast cancer incidence therefore is quite low under the age of 40, and then begins to rise as women age.

The major risk factors that put you in a higher risk group for breast cancer are a personal or family history of ovarian, peritoneal (including tubal), or breast cancer. A known genetic predisposition e.g. BRCA as well as a history of radiotherapy to the chest between age 10 and age 30, are also risk factors.


When should I go for a mammogram?

For women at average risk, meaning women who do not have a gene that increases their risk of breast cancer or close relatives who had breast cancer at an early age, expert groups differ in their advice about when to actually start screening. If you are at average risk, we should start discussing breast cancer screening once you turn 40. If you have not initiated screening in your 40’s, you should begin screening mammography by no later than age 50.

It is not clear what the ideal schedule for screening should be. Many experts suggest mammograms every two years for most average-risk women. Other experts suggest mammograms every year. Ideally this decision should be an individualised, shared decision made during your consultation and based on your risk as well as your preferences. The schedule for screening might also be different if you are found to have a high risk of breast cancer.

When we discuss your specific risk for breast cancer, one person might opt for screening if she has concerns about breast cancer risk and accept the possibility of a false-positive result or over-diagnosis and the resulting treatment that could follow as discussed above. Another woman may feel that the frequency of false positives and over-diagnosis provide a compelling reason for her to defer screening.


What are the current recommendations for screening from the Radiology Society of South Africa?

  1. Annual mammograms for women older than 40 years and younger than 70 years.
  2. Annually in conjunction with MRI for all women with a calculated risk of 20% or greater. In patients with a family history, screening should start at age 40 or 5 years before the age at which the relative was diagnosed, if this is earlier than 40 years.


What are the implications if I have dense breast tissue?

Dense breast tissue refers to the breast tissue appearing relatively white on a mammogram. An abnormality (a lump or calcification) is also white.  It is more difficult to detect a white abnormality against a white background as opposed to detecting a white abnormality against a dark background, as is the case in non-dense breast tissue. An ultrasound of the breast or a tomogram may therefore be done in addition to the mammogram.

Dense breast tissue is not abnormal and is a common finding on mammogram.  Almost half of women have dense breast tissue.

It is however important to be aware that recent research has shown that your risk of developing breast cancer is slightly higher if you have dense breast tissue. This risk is comparable to the risk you would have if a family member had breast cancer and is also dependent on the degree of breast density.

If you have dense breasts consider annual screening. Currently research is being done on the use of a tomogram as a way of tailoring mammograms to better assess women with dense breasts.


When is a breast MRI indicated?

A breast MRI is advised for the screening of high risk women e.g. known BRCA mutation (genetic familial cancers), as well as those that had radiation to the chest area as a child.


Can I choose to just do my own breast self-examinations?

Several research studies over the last few years have shown a lack of benefit with routine breast self-examinations. Some studies have even shown that this leads to a higher chance of breast biopsies showing benign disease. Many expert groups therefore do not encourage breast self-examination.

The World Health Organisation however does see breast self-examination as a way to empower women and raise awareness among women at risk, rather than as a screening method. Breast self-examination should be seen as an adjunct, but not a substitute, for mammography.

During your consultation and examination you will be encouraged to have awareness of the normal appearance and feel of your breasts. You should notify us immediately if you experience a change.


I understand that screening aims to detect breast cancer, but how can I lower my risk of developing breast cancer?

Good news is that a healthy lifestyle has been shown to lower your risk of breast cancer. Achieve this by having a healthy diet, maintaining an exercise regimen, limiting alcohol intake and controlling post-menopausal weight gain. If you are very high risk we will discuss certain preventive medications and in extremely high risk cases preventive surgery will be considered.

Bottom line

A mammogram is the best screening test available to detect breast cancer at an early stage. It is important to understand the risks of a false positive test as explained above. Your individual risk and a personalised plan will be discussed during consultation to enable you to make an informed decision.