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Your Questions about Breast Cancer Screening, Diagnosis, and Local Follow-up
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When do we have to undergo mammography ?
- Outside screening :
mammography is useless in children and teenagers. In women younger than 35 years old (possible age of first screening) we can perform a mammography if they present a clinical symptom and if the problem can't be solved by ultrasound only, or if their mother developed breast cancer very early (before 35 years old).
- Within the context of screening :
mammography, an X-ray examination of breast, is the bedrock of screening, a first-place examination. It is always useful, even in dense breasts. It is the only examination that clearly shows one of the earliest signs of breast cancer : microcalcifications.
Careful, microcalcifications can be harmless and thus may not represent any danger; moreover, they do not herald cancer systematically. Microcalcifications are easy to detect in dense breasts. Mammography is also an efficient examination to detect changes in breast structure (changes that are also easy to see in dense breasts).
How does breast cancer look on the scan ?
In mammograms we can notice three signs that clearly show the development of cancer :
- irregular shadow (which is white on the mammogram)
- changes in the breast usual structure
- microcalcifications that appear like fine white dust on the mammogram and may be the earliest sign of a cancer which starts and is located in a milk duct ("in situ" cancer, the prognosis of which is good)
As for ultrasound, it enables to detect a cancer which appears like an irregular grey/black mass that can already be detected when it is 3-4mm thick. Sometimes, it enables to detect microcalcifications (when there are abundant) by means of newly-created efficient device.
Is there any injury that we can't see on the mammograph or on the ultrasound ?
- Yes, when the injury is too small that it can't be detected, but in this case, given the average rate of tumour development, it should be detected by another screening, as long as the duration between the two examinations is optimal ; that is to say, once a year. A 1mm³ thick tumour (1cubic millimetre) is made up of 1 million cells but it still can't be detected. On average, a tumour needs six years to pass from one cell to one million cells
- Yes, 5 to 10% of cancers can only be seen on ultrasounds. Usually, they are very small tumours of less than 1cm.
When do we have to get an ultrasound ?
- when an abnormality is detected in a child or a teenager.
- When the last mammography took place less than one year ago and the patient presents a symptom that looks harmless (for instance : cyst)
- In addition to a screening mammography. We know that in this case, ultrasound can detect abnormalities that mammography did not see.
- When an abnormality has been detected and we want to know its nature. For instance, we discover a kind of round shadow on the mammography, so an ultrasound enables then to give more details and show that it is a common cyst made up of water.
What is the part of the CT scan or the breast resonance ?
They are called third-place examinations.
When we detect a clinical abnormality, first we perform a mammography (first-place examination) that may be followed by a second-place ultrasound. If these two techniques do not manage to diagnose, we can require a third-place examination which is the resonance (MRI) or the CT scan (CT). These examinations are very sensitive; that is to say, they are very efficient to detect small changes in breast but they are less specific; in other words, the abnormalities that are detected do not necessarily correspond to a cancer. When the radiologist detects a suspicious injury of breast cancer, his part is to give more precision about the cancer spreading and to determine if the disease (cancer) is in situ or if there are other injuries in the same breast, in the other breast or even outside the breast (metastasis). All this information will allow to establish a first treatment for the patient. The MRI plays a significant part in this mission but the device is not available everywhere.
What do we have to do when we discover an abnormality on the scan ?
When the abnormality is palpable and even if it can only be seen by imaging techniques, we can take samplings :
- by means of a fine needle which removes cells or liquid (when we aspirate a cyst) : aspiration cytology.
- by means of a larger gauge needle (microbiopsy) or an even larger gauge needle (macrobiopsy) : we remove a fragment of breast tissue which is then put under the microscope. These biopsies are performed under local anaesthesia. The samplings can be removed in order to confirm that a lump is harmless (in this case, the lump does not have to be removed) or, when it is question of cancer, to get information about the microscopic characteristics of cancerous cells. These characteristics may be essential to establish a treatment.
Are tissue samplings dangerous when they are withdrawn from a cancerous nodule ?
Lots of studies have shown that these samplings are not dangerous. When cancerous tissue is removed, it is said that the cancerous cells that may be moved during the sampling die rapidly when they are outside the lump and can't develop a new tumour or send cells in blood circulation
Are diagnoses techniques reliable ?
The full mastology examination that includes the clinical examination, the mammography and the ultrasound is very reliable (more than 98% of diagnosis reliability) as long as the whole procedure is checked by a quality control (mammographs, ultrasound device, films and films development) and the examination is carried out by a qualified radiologist
Are diagnoses techniques dangerous regarding radiation ?
Mammography requires the using of X-rays while the ultrasound uses ultrasounds. The ultrasound does not have any known carcinogenic effect. Since the breast is a subcutaneous organ, there are few tissues to go through and thus the mammography uses very weak x-rays (0.05 rad). We live in a natural, radiant environment in which the dose of X-rays present in the air is very different according to the location. In our region, on average, we are exposed to about 1rad in 10 years (which is the equivalent of 20 mammographies).
The benefit that doing screening presents is 25 times higher than the theoretical risk of exposure to X-rays. However, it is better not to undergo mammography more than it is required.
How is it possible to discover a cellular biomass several months following a mammography ?
- This may be due to tumour's rate of development that is higher than average. A tumour volume doubles every 100 days. When only one cell is ill in the breast, it needs about 8 years for the tumour to be clinically detectable by palpation.
- After two years, the number of cancerous cells is still lower than 1000 and may still disappear by the action of the organism immune system.
- After 5 years, the lump size is about 1mm (1 million cells). In that case, the cancerous cells are still sensitive.
- In the eighth year, the tumour becomes detectable (1 gram or 1 billion cells), it is linked to the veins (cancer cannot disappear any more spontaneously). Since it doubles every 3 months (100 days), it achieves the size of 15 grams (15 mm) one year later.
- Therefore, most of the time a tumour is detectable through examinations that we have already talked about, before we can clinically palpate it between the seventh and the eighth year of development. In general, its size is about 5 to 8 mm (more than 1mm but less than 1 cm).
If the tumour develops rapidly, the development rate is divided by four and thus, the tumour may become palpable after a negative screening examination and before the following screening examination, even if the duration between the two examinations is only one year.
If the period of time between two mammographies is too large, it is easy to understand why a lump may be detected between two screenings.
If the mastology quality control of radiographs or/ and reading is not good enough, a detectable injury may have not been seen.
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