NCCN Guidelines for Patients
Breast Cancer - Early-Stage
(STAGES I AND II)
, Version 1.2016
Cancer is a disease of cells. Carcinomas are cancers
of cells that make up the skin and the tissue that
lines or covers organs. Almost all breast cancers are
carcinomas. In the breast, carcinomas start in the
cells lining either the ducts or lobules, but most breast
cancers start in ductal cells.
Inside of cells are coded instructions for building
new cells and controlling how cells behave. These
instructions are called genes. Genes are a part
of DNA (
cid), which is grouped
together into bundles called chromosomes.
Abnormal changes (mutations) in
genes cause normal cells to become cancer cells.
Researchers are still trying to learn what causes
genes to mutate and cause cancer.
Cancer cells don’t behave like normal cells in three
key ways. First, mutations in genes cause normal
cells to grow more quickly and live longer. Normal
cells grow and then divide to form new cells when
needed. They also die when old or damaged as
. In contrast, cancer cells make
new cells that aren’t needed and don’t die quickly
when old or damaged. Over time, breast cancer cells
form a mass called the primary tumor.
The second way cancer cells differ from normal
cells is that they can grow into surrounding tissues.
If not treated, the primary tumor can extend beyond
the walls of lobules or ducts into the stroma. Breast
cancers that haven’t grown into the stroma are called
“noninvasive breast cancer.” Breast cancers that have
grown into the stroma, such as stages I and II, are
called “invasive breast cancer.”
Third, unlike normal cells, cancer cells can leave the
breast and form tumors in other parts of the body.
This process is called metastasis. In this process,
cancer cells break away from the tumor and merge
with blood or lymph. Then, the cancer cells travel
in blood or lymph through vessels to other sites.
The first site is your axillary lymph nodes. Common
distant sites include your bones, lungs, brain, and
liver. Once cancer cells are in other sites, they can
form secondary tumors and may cause major health
Breast cancer basics