Synonyms in a broader sense
Breast carcinoma, breast-Ca, invasive ductal breast carcinoma, invasive lobular breast carcinoma, inflammatory breast carcinoma, Paget’s disease, carcinoma in situ
Is breast cancer equal to breast cancer?
In principle, there are many different types of breast cancer, depending on the cell type from which the cancer originally develops. However, some of these breast cancers are very rare and in practice play only a minor role. The two most important breast cancers develop from the cells of the milk ducts (ductuli = lat.
duct) and the mammary gland lobules (lobuli = lat. lobules) and are therefore called “ductal” and “lobular” breast cancer. 85-90% of breast cancer cases originate from the tissue of the mammary ducts, i.e. they are ductal carcinomas.
The decisive factor is whether the tumour grows inside the milk ducts and their outer boundary – also called basal membrane – is intact or whether the tumour has grown beyond this boundary into the adjacent tissue. A further distinction is made between non-invasively growing precancerous lesions, also known as carcinomas in situ, in which the external border is intact, and invasively growing carcinomas in which the tumour has crossed the external border. This distinction is important because it has an impact on the prognosis of breast cancer and the treatment options.
Lobular breast cancer is responsible for 10-15% of cancer cases. Here, too, a distinction is made between non-invasive and invasively growing tumours. If the tumour is restricted to the tissue of the mammary glands, it is called lobular carcinoma in situ, if it grows beyond the tissue, it is called invasive lobular carcinoma.
Breast cancer: Classification
WHO classification of 2001 A. Non-invasive tumours B. Invasive breast carcinomas C. Special forms
- Common carcinomas: ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS)
- Common carcinomas: invasive ductal breast carcinoma, invasive lobular breast carcinoma
- Rare carcinomas: mucinous breast carcinoma, medullary breast carcinoma, papillary breast carcinoma, tubular breast carcinoma, apocrine breast carcinoma
- Common carcinomas: Paget’s disease of the nipple, inflammatory breast carcinoma
Carcinoma in situ
A carcinoma in situ is a malignant tissue proliferation that grows non-invasively into the tissue. This means that its growth is limited to a superficial tissue layer. It is therefore a preliminary stage of cancer that can still be treated surgically.
If it is removed completely, degeneration into an invasive form of cancer is no longer possible in most cases. However, if a carcinoma is left in situ, there is a risk of degeneration, which is only a question of time depending on the individual and the nature of the cancer. The “DCIS” is sometimes also called precancerous stage (precancerosis).
Since it has not yet broken through the basement membrane, no metastases can have formed. The transition period from a DCIS to an invasive ductal carcinoma is estimated to be less than ten years. Clear evidence that a finding is a carcinoma in situ can only be provided by the pathologist (examining the breast cancer tissue sample) after the entire suspicious area has been removed.
Before that, none of the imaging procedures can rule out the possibility that the suspicious area has not ruptured the basement membrane at a small point and thus developed into invasive (displacing) growth. However, even with the most careful examination of the tissue by the pathologist, the latter is not always able to provide reliable information as to whether the basement membrane has remained intact. If the tumour has expanded by more than 5 cm, there is a 60 % probability that invasive growth through the basement membrane has occurred.
Not every DCIS develops into an invasive form. It is assumed that approx. 50 % of DCIS will become invasive later, but there is no reliable data on this.
DCIS occurs independently in both breasts in 10 – 30 % of cases. A duktual carcinoma in situ is usually not palpable as a lump or hardening in the breast, and the ultrasound usually does not show any of the findings. Most often DCIS is discovered by chance through mammography screening (see: Mammography).
Most suspicious are scattered calcific lesions, so-called microcalcifications, which are often not larger than one millimeter in the image, but appear bright white due to their composition. This does not mean, however, that a DCIS is hidden behind every calcification in mammography. Also, not every DCIS due to calcifications is visible in mammography.
