In situ carcinoma
Cancers cells that do not spread outside the duct are called in situ cancers ("in situ" means "in place"). These are pre-invasive cancers but they can either develop into invasive breast cancer or raise your risk of getting invasive cancer.
Ductal Carcinoma In Situ (DCIS)
Ductal Carcinoma In Situ (or DCIS) refers to cancer cells which still remain inside the breast ducts. It is often referred to as a pre-cancer. If left untreated it may develop in to invasive cancer. DCIS is usually diagnosed on a mammogram where specks of calcium can be seen. Usually there are no symptoms although occasionally women may present with a discharge from the nipple, or a lump may be felt.
DCIS is generally treated with surgery. If the area is small then wide excision or partial mastectomy may be performed. This may be followed with breast radiotherapy. If the DCIS is widespread throughout the breast then full mastectomy ( removal of the whole breast ) may be necessary.
Lobular Carcinoma In Situ (LCIS)
Also known as lobular neoplasia. LCIS is not even a pre-cancer but if present in the breast it does signal an increased chance of developing invasive cancer in either breast in the future and is a marker of disease risk. LCIS is only found on a biopsy and usually doesn't require further removal. It can not be seen on mammogram and does not cause any symptoms. The usual treatment is regular monitoring so that if a cancer does develop it will be detected early.
Clinical trials have shown that hormone-blocking therapy, such as tamoxifen and anastrozole, reduces the risk of breast cancer in women with LCIS but the risks and side effects of treatment may outweigh the benefit for many women. You may wish to discuss this with your doctor.
When cancers spread out of the ducts into surrounding breast tissue, the cancer is called invasive or infiltrating. Most (90%) invasive breast cancers are ductal cancers. Breast cancers do two things as they grow. They spread locally in the breast ) and can send cells through the blood and lymph channels to other sites (metastasis). Metastasis (spreading to other parts of the body) is also called secondary cancer.
Invasive lobular carcinoma is a cancer that has spread from the lobules to surrounding tissue. It is often found in several different places within the breast and sometimes in both breasts. It can be difficult to detect by physical examination or mammography.
HER2 positive mean that the breast cancer cells have higher than normal levels of a protein called HER2. This is most commonly treated with a biological agent called Herceptin. Around 20% of breast cancer cases in New Zealand are HER2 positive.