Most breast cancers arise from the epithelia in the breast, and these are known as carcinomas. In-situ carcinoma is the term used for a carcinoma which remains in the position in which it developed, with no sign of invasion into the surrounding tissues. Sarcomas – tumours arising from the connective tissue -are rare in the breast.
Some 90 per cent of breast cancers develop within the epithelial lining of the ducts. Of the remainder, about 5 per cent occur within the lobules of the breast, and these are likely to be associated with second tumours in the same or the other breast. The remaining 5 per cent are a combination of ductal and lobular cancers. There are variant forms of most types of breast cancer, sometimes with a different prognosis from that of the tumours they resemble.
Different names are used to identify the same cancers in different countries, and by different doctors within a country. Confusion is therefore rife – not least amongst the medical profession itself.
Ductal tumours
Scirrhous/non-specific ductal carcinoma
This is the most common form of ductal breast cancer, which usually develops as a hard, painless swelling in women near their menopause. It often occurs in the upper outer quadrant of the breast and may spread into the surrounding fat. Malignant cells may also be present in nearby lymph vessels and blood capillaries. A scirrhous carcinoma that has invaded the lymph nodes or the lymph vessels near the skin is likely to have a worse prognosis.
Atrophic scirrhous carcinoma
This is a very slow-growing tumour which may cause contraction and deformity of the breast in elderly women. It is often only found during routine medical examination and can remain localized in the breast for many years.
Medullary carcinoma
Also called lymphocytic or encephaloid carcinoma, this is a softer, more rapidly growing tumour than the scirrhous. It is said to have a better prognosis, even when spread has occurred to the lymph nodes in the armpits. If the body launches a strong defensive response itself, the prognosis can be even better. There is less fibrous reaction (unlike with the scirrhous type), and many disease-fighting lymphocytes are seen within the cancer.
There is also a variant of this type of cancer which is known as atypical medullary carcinoma. This is an intermediate form combining characteristics of a medullary and a scirrhous carcinoma.
Inflammatory carcinoma/carcinoma of pregnancy and lactation
These tumours may resemble a breast abscess. They grow rapidly and may cause the breast to become hot and tender. They do not normally become apparent until it is too late for them to be treated successfully.
Papillary carcinoma
Papillary carcinomas are a rare variant of the non-specific ductal form, with a good prognosis. They develop as a mass of cells within the lumen of a duct, and they present early with bloody nipple discharge.
Cystic carcinoma
Cystic carcinomas are rare (only about 1 per cent of all breast cancers), but they have a poor prognosis. When aspirated, the fluid they contain is bloody, and malignant cells can be seen within it when it is examined under a microscope.
Lobular tumours
Cancers in the lobules of the breast are 10 to 20 times less common than ductal tumours. The prognoses are similar, but lobular tumours are more likely to occur in both breasts, Sometimes several being present at the same time.
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