NCCN Guidelines for Patients
Ovarian Cancer, Version 1.2017
Cancer cells make new cells that aren’t needed
and don’t die quickly when old or damaged. Over
time, cancer cells grow and divide enough to form
a mass called a tumor. The first tumor formed by
the overgrowth of cancer cells is called the primary
Types of ovarian cancer
The ovaries are made up of three main types of cells:
epithelial cells, stromal cells, and germ cells. Cancer
can start in each type of cell. Thus, there is more
than one type of ovarian cancer.
Most ovarian cancers start in the epithelial cells.
This is called epithelial ovarian cancer. Epithelial
cells form the outer layer of tissue around the
ovary. This layer of tissue is called the epithelium.
See Figure 3.
About 90 out of 100 ovarian cancers
are epithelial ovarian cancer. Because it is the most
common type, it is often simply referred to as ovarian
Borderline epithelial tumors [LMP (
otential] also start in the epithelial cells. It is a rare
type of epithelial ovarian cancer. LMP tumors don’t
grow into the supporting tissue of the ovary. The
tumor cells may spread and grow on the surface of
nearby organs and tissues. But, they almost never
grow into (invade) tissue the way fully cancerous
This guideline also discusses other LCOH (
carcinosarcomas (MMMTs [
umors) of the ovary, clear cell carcinomas,
mucinous carcinomas, low-grade (grade 1) serous
carcinomas/endometrioid epithelial carcinomas,
malignant sex cord-stromal tumors, and malignant
germ cell tumors.
It is helpful to understand that the terms carcinoma
and malignant both refer to cancer when used in the
names of the LCOH. The term carcinoma means
cancer that starts in the cells that form glands or the
lining or organs. Malignant is also used in the names
and also means cancer.
Cancer cells act differently than normal cells in three
key ways. First, cancer cells grow without control.
Unlike normal cells, cancer cells make new cells that
aren’t needed and don’t die when they should. The
cancer cells build up to form a primary tumor.
Second, cancer cells can grow into (invade) other
tissues. This is called invasion. Normal cells don’t
do this. Over time, the primary tumor can grow large
and invade tissues outside the ovary. Ovarian cancer
often invades the fallopian tubes and uterus.
Third, cancer cells don’t stay in one place as they
should. Unlike normal cells, cancer cells can spread
to other parts of the body. This process is called
metastasis. Ovarian cancer cells can break off
(shed) from the primary tumor to form new tumors
on the surface of nearby organs and tissues. These
are called “implants” or “seeds.” Implants that grow
into supporting tissues of nearby organs are called
Cancer cells can also spread through blood or lymph
vessels. Lymph is a clear fluid that gives cells water
and food. It also has white blood cells that help fight
germs. It travels in small tubes (vessels) to lymph
nodes. Lymph nodes are small groups of disease-
fighting cells that remove germs from lymph. Lymph
vessels and nodes are found all over the body.