NCCN Guidelines for Patients® | Stage 0 Breast Cancer - page 8

6
NCCN Guidelines for Patients
®
Stage 0 Breast Cancer, Version 1.2014
1
Breast cancer
basics
6 Women’s breasts
6 Carcinoma in situ
7 Cancer growth
8 Review
Women’s breasts
Before puberty, breasts have a ring of darker skin
called the areola. In the middle of the areola is the
raised tip of the breast called the nipple. Under the
nipple, small milk ducts branch into fatty tissue like
early growth from a seedling. These immature ducts
are supported by connective tissue called stroma.
Among girls, increases in female hormones during
puberty cause their breasts to change. The stroma
increases, the ducts grow and branch out like tree
limbs, and lobules form at the end of the ducts like
leafs at the end of twigs. Lobules are small sacs that
make breast milk after a baby is born. Breast milk
drains from the millions of leaf-like lobules into the
milk ducts that connect to the nipple.
See Figure 1
for
a look inside women’s breasts.
Carcinoma in situ
Breast cancer is a disease of cells—the building
blocks of tissue in the body. Almost all breast cancers
are “carcinomas.” Carcinomas are a family of cancers
that begin in cells that line the inner or outer surfaces
of the body. Examples include surfaces of ducts and
the gut and skin.
This book focuses on carcinoma in
situ of the breast. “In situ” means that
no abnormal cells have grown into the
stroma. Carcinoma in situ is stage 0
breast cancer.
The two kinds of carcinoma in situ are:
LCIS
(
l
obular
c
arcinoma
i
n
s
itu) – Although
called a carcinoma, LCIS isn’t cancer but
abnormal cell growth within the lobules; and
DCIS
(
d
uctal
c
arcinoma
i
n
s
itu) – DCIS is
cancer that started in ductal cells and hasn’t
grown outside the milk ducts.
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