Ductal carcinoma in situ
Most breast cancers (carcinomas) arise in cells that line the ducts and lobules of the breast. We still don't know what happens exactly, but for some reason the cells start growing when they are not supposed to be growing. When cells in the lining of breast ducts are growing inappropriately, this is called hyperplasia; when they grow inappropriately and do not appear normal under the microscope, they are called atypical hyperplasia.
DCIS is a term used to describe cells that are growing inappropriately inside the ducts of the breast (see diagram) and look like cancer cells under the microscope. These abnormal cells have not spread into the surrounding fatty breast tissue or to any other part of the body. They are totally confined to the duct.
Some cell changes are important, while others are less important. DCIS cells lack the biological capacity to metastasize, or spread elsewhere in the body, like cancer cells do. So why do DCIS cells fall into the category of cancer cells?
Some DCIS cells can change genetically and become true cancers, and women should not be lulled into thinking that a DCIS diagnosis can be ignored or dismissed. We still do not know for sure which DCIS cells will change and become invasive and which will remain DCIS. It is probably most useful to view a diagnosis of DCIS as an indication that a woman has a greater risk of developing breast cancer, especially if she receives no treatment for the DCIS.
Data suggests that ductal carcinoma in situ represents a stage in the development of breast cancer in which most of the changes that characterize invasive breast cancer are already present.
There are different kinds of DCIS. It is important for the individual who is diagnosed with DCIS to know how aggressive or risky her cell type is. For example, comedo is considered more aggressive (high-grade) than cribiform (low-grade). This information is part of an accurate diagnosis by the pathologist, and helps define treatment options, which in turn affects whether DCIS becomes invasive breast cancer.
A diagnosis of DCIS depends on the pathologist, and the diagnosis may be controversial. Therefore, second opinions may be important. If a woman seeks a second opinion, she needs to take her tissue slides and tissue blocks that contain samples of the cells taken during her biopsy to another pathologist, and she must be prepared to pay for this additional opinion. A pathologist is a physician who looks at cells under a microscope.
People often fail to get a second opinion for pathology. However, if the pathology is incorrect, the treatment choices are much more likely to be incorrect and possibly ineffective as well.
You can also request second opinions for mammography, ultrasound, and treatment. If you choose to have a second opinion for mammography or ultrasound, it is important to take the original films, not copies, to the physician, and to carry them to the radiologist yourself if possible.
Whether your doctor refers to DCIS as cancer or pre-cancer, it requires careful treatment and follow-up to avoid the possibility of an invasive breast cancer developing.
There is a lot of research going on that will help sort out which kinds of DCIS are aggressive and how to determine optimal treatment for each kind.
In this web site, we refer to DCIS as a cancer.