43
Cell Biology and Cancer
benign: Not cancerous; does not invade nearby
brachytherapy: Internal radiation therapy using
tissue or spread to other parts of the body.
an implant of radioactive material placed directly
into or near the tumor.
benign tumor: Noncancerous growth that does
not spread to other parts of the body.
BRCA1: Gene located on chromosome 17 that
normally helps restrain cell growth. Inheriting
biological therapy: Treatment to boost or restore
certain altered versions of BRCA1 predisposes an
the ability of the body’s immune system, either
individual to breast, ovarian, prostate, or other
directly or indirectly, to fight cancer or to lessen
types of cancer.
side effects that may be caused by some cancer
treatments. Also known as immunotherapy,
BRCA2: Gene located on chromosome 13 that
biotherapy, or biological-response-modifier therapy.
normally helps to suppress cell growth. A person
who inherits certain changes in BRCA2 has a
biopsy: Removal of a sample of cells or tissue,
higher risk of breast, ovarian, prostate, or other
which is then examined under a microscope or
types of cancer.
with other tests to check for cancer cells.
breast reconstruction: Surgery to rebuild a
bone marrow: Soft, spongy tissue in the center
breast’s shape after a mastectomy.
of large bones that produces white blood cells,
red blood cells, and platelets.
Burkitt lymphoma: Type of non-Hodgkin
lymphoma that most often occurs in children
bone marrow aspiration: Removal of a small
and young adults. The disease causes a rapidly
sample of bone marrow (usually from the hip
growing tumor in the abdomen, jaw, or central
bone, breast bone, or thigh bone) through a
nervous system.
needle for examination under a microscope
to see whether cancer cells are present. This
cancer: Term for a group of more than 100
procedure may be done at the same time as a
diseases in which abnormal cells divide without
bone marrow biopsy.
control. Cancer cells can invade nearby tissues
and can spread through the bloodstream and
bone marrow biopsy: Removal of a sample of
lymphatic system to other parts of the body.
bone with bone marrow inside it using a large
needle. The cells are checked to see whether
cancer stem cells: A small population of cells
they are cancerous. If cancerous plasma cells are
inside tumors that have the ability to self-renew
found, the pathologist estimates how much of the
while giving rise to different types of cells. It is
bone marrow is affected.
thought that cancer stem cells might be resistant
to many cancer drugs and may reconstitute a
bone marrow transplantation: Procedure in
tumor after chemotherapy has eradicated the bulk
which doctors replace marrow destroyed by
of tumor cells.
treatment with high doses of anticancer drugs
or radiation. The replacement marrow may be
carcinogen: Any substance that is known to
taken from the patient before treatment or may
cause cancer.
be donated by another person.
carcinogenesis: Process by which normal cells
bone scan: Technique to create images of bones
are transformed into cancer cells.
on a computer screen or on film. A small amount
of radioactive material is injected and travels
carcinoma: Cancer that begins in the skin or in
through the bloodstream. It collects in the
tissues lining or covering of an organ.
bones, especially in abnormal areas of the
bones, and is detected by a scanner.
carcinoma in situ: A group of abnormal cells that
remain in the place where they first formed. They
have not spread to other tissues.
44
CEA assay: Laboratory test to measure the level of
computed tomography: X-ray procedure that
carcinoembryonic antigen (CEA), a substance that
uses a computer to produce a detailed picture
is sometimes found in an increased amount in the
of a cross-section of the body; also called CAT
blood of patients with certain cancers, with some
or CT scan.
other diseases, or who smoke.
contact inhibition: Inhibition of cell division in
cell cycle: Sequence of events by which cells
normal (noncancerous) cells when they contact a
enlarge and divide. Includes stages typically
neighboring cell.
named G1, S, G2, and M.
CT (or CAT) scan: See computed tomography.
chemoprevention: Use of natural or laboratory-
made substances to reduce the risk of, or delay
cytokine: A substance produced by cells of the
the development or recurrence of, cancer.
immune system that can affect the immune
response. Cytokines can also be produced in the
chemotherapy: Treatment with anticancer drugs.
laboratory by recombinant DNA technology and
given to people to affect immune responses.
chronic lymphocytic leukemia: A disease in
which too many infection-fighting lymphocytes
cytotoxic: Poisonous to cells. In chemotherapy,
(white blood cells) are found in the body. The
used to describe an agent that is poisonous to
developing lymphocytes do not mature correctly
cancer cells.
and too many are made. The lymphocytes cannot
fight infection as they should and are found in the
death rate: Number of deaths per 100,000 people
blood and the bone marrow. Chronic lymphocytic
per year; also called mortality rate.
leukemia normally progresses slowly and usually
occurs in people over 60 years of age.
diagnosis: Process of identifying a disease by the
signs and symptoms.
chronic myelogenous leukemia: A disease in
which too many white blood cells are made in
dysplasia: Abnormal cells that are not cancer.
the bone marrow. Chronic myelogenous leukemia
affects the cells that develop into specific white
dysplastic nevi: Atypical moles; moles whose
blood cells called granulocytes. The cells do
appearance is different from that of common
not mature and become too numerous. The
moles. Dysplastic nevi are generally larger than
immature cells are then found in the blood and
ordinary moles and have irregular or indistinct
bone marrow. This disease progresses slowly and
borders. Their color often is not uniform and
usually occurs in people who are middle-aged or
ranges from pink or even white to dark brown
older, although it can occur in children.
or black; they are usually flat, but parts may be
raised above the skin surface.
clinical trial: Research study that involves
patients. Each study is designed to find better
encapsulated: Confined to a specific area and
ways to prevent, detect, diagnose, or treat cancer
surrounded by a thin layer of tissue.
and to answer scientific questions.
endometrial: Having to do with the endometrium,
colonoscopy: Procedure that uses a flexible fiber
the layer of tissue that lines the uterus.
optic endoscope to examine the internal surface of
the colon along its entire length.
environmental tobacco smoke: Smoke that
comes from the burning end of a cigarette
combination chemotherapy: Treatment in which
or other smoked tobacco product and smoke
two or more chemicals are used to obtain more-
that is exhaled by smokers. Also called ETS
effective results.
or secondhand smoke. Inhaling ETS is called
involuntary or passive smoking.
45
Glossary
Cell Biology and Cancer
epidemiology: Study of the patterns, causes, and
genome-wide association study (GWAS): An
control of disease in groups of people.
approach that involves scanning markers across
the complete sets of DNA, or genomes, of many
epidermis: Upper or outer layer of the two main
people to find genetic variations associated with
layers of cells that make up the skin.
a particular disease. Such studies are particularly
useful in finding genetic variants that contribute to
Epstein-Barr virus: Virus that has been
common, complex diseases, such as asthma, cancer,
associated with the development of infectious
diabetes, heart disease, and mental illnesses. Once
mononucleosis and also with certain cancers
new genetic associations are identified, researchers
including Burkitt lymphoma.
can use the information to develop better strategies
to detect, treat, and prevent the disease.
estrogen: Female hormone produced by the ovary.
Responsible for secondary sex characteristics
grade: Describes how closely a cancer resembles
and cyclic changes in the lining of the uterus
normal tissue of its same type, along with the
and vagina.
cancer’s probable rate of growth and tendency
to spread.
etiology: The cause or origin of disease.
grading: System for classifying cancer cells in
familial polyposis: Inherited condition in which
terms of how malignant or aggressive they appear
several hundred polyps develop in the colon and
microscopically. The grading of a tumor indicates
rectum. These polyps have a high potential to
how quickly cancer cells are likely to spread and
become malignant.
plays a role in treatment decisions.
fecal occult blood test: Test to reveal blood in
herpes virus: Member of the herpes family of
the feces, which may be a sign of colon cancer.
viruses. One type of herpes virus is sexually
transmitted and causes sores on the genitals.
fiber: Parts of fruits and vegetables that cannot
be digested. Also called bulk or roughage.
heterozygous/heterozygosity: Possessing two
different forms of a particular gene, one inherited
fibroid: Benign smooth-muscle tumor, usually in
from each parent.
the uterus or gastrointestinal tract.
homozygous/homozygosity: Possessing two
gene: The basic unit of heredity.
identical forms of a particular gene, one inherited
from each parent.
gene therapy: An experimental treatment in
which foreign genetic material (DNA or RNA)
hormonal therapy: Treatment of cancer by
is inserted into a person’s cells. In studies of
removing, blocking, or adding hormones.
gene therapy for cancer, researchers are trying
to improve the body’s natural ability to fight the
human papillomaviruses: Viruses that can cause
disease or to make the tumor more sensitive to
abnormal tissue growth. Some papillomaviruses
other kinds of therapy.
are sexually transmitted. Some of these sexually
transmitted viruses cause wartlike growths on
genetic: Inherited; having to do with information
the genitals. Long-term infections of certain types
that is passed from parents to children through
of papillomaviruses can cause cervical cancer.
DNA in the genes.
Papillomaviruses may also play a role in cancers
of the anus, vagina, vulva, penis, skin, and throat.
genome: The complete genetic material of
an organism.
hyperplasia: Precancerous condition in which
there is an increase in the number of normal cells
in an organ or tissue.
46
imaging: Tests that produce pictures of areas
melanocyte: Cell in the skin and eyes that
inside the body.
produces and contains the pigment called
melanin.
immunotherapy: Treatment to boost or restore
the ability of the immune system to fight cancer,
melanoma: Cancer of the cells that produce
infections, and other diseases. Also called
melanin. Melanoma usually begins in a mole but
biotherapy or biological-modifier-response therapy.
can also begin in other pigmented tissues, such as
in the eye.
incidence: Number of new cases of a disease
diagnosed each year.
metastasis: The spread of cancer from one part of
the body to another.
incidence rate: Number of new cases per year
per 100,000 people.
metastasize: To spread from one part of the
body to another. When cancer cells metastasize
in situ cancer: Cancer that has remained within
and form secondary tumors, the cells in the
the tissue in which it originated.
metastatic tumor are like those in the original
(primary) tumor.
invasion: As related to cancer, the spread of cancer
cells into healthy tissue adjacent to the tumor.
mole: A benign growth on the skin (usually
dark in color) that is formed by a cluster of
invasive cancer: Cancer that has spread beyond
melanocytes. See also nevus.
the layer of tissue in which it developed.
monoclonal: Population of cells that was derived
keratin: Insoluble protein that is the major
by cell division from a single ancestral cell.
constituent of the outer layer of the skin, nails,
and hair.
morbidity: Disease.
lesion: Area of abnormal tissue.
mortality: Death.
leukemia: Cancer of the blood-forming tissue,
mutagen: Any substance that is known to cause
such as the bone marrow, which causes large
mutations.
numbers of cells to be produced and enter the
bloodstream.
mutagenesis: Process by which mutations occur.
lifetime risk: Probability that a person, over the
mutation: Any change in the DNA of a cell.
course of a lifetime, will develop a type of cancer.
Mutations may be caused by mistakes during
cell division, or they may be caused by exposure
Li-Fraumeni syndrome: Rare family
to DNA-damaging agents in the environment.
predisposition to multiple cancers, caused by an
Mutations can be harmful, beneficial, or have no
alteration in the p53 tumor-suppressor gene.
effect. If they occur in cells that make eggs or
sperm, they can be inherited; if mutations occur in
lumen: The cavity or channel within a tube or
other types of cells, they are not inherited. Certain
tubular organ, such as the lumen of the gut.
mutations may lead to cancer or other diseases.
malignant: Cancerous; can invade nearby tissue
National Cancer Institute (NCI): The largest of
and spread to other parts of the body.
the 27 separate institutes, centers, and divisions
of the National Institutes of Health. The NCI
melanin: Skin pigment (substance that gives the
coordinates the federal government’s cancer
skin its color). Dark-skinned people have more
research program.
melanin than do light-skinned people.
47
Glossary
Cell Biology and Cancer
National Institutes of Health (NIH): One of
oncology: Study of cancer encompassing its
eight health agencies of the Public Health Service
physical, chemical, and biologic properties.
(the Public Health Service is part of the U.S.
Department of Health and Human Services).
oopherectomy: Surgical removal of one or
Composed of 27 separate institutes and centers,
both ovaries.
NIH is the largest biomedical research facility in
the world.
p53: Gene that normally inhibits the growth of
tumors, which can prevent or slow the spread
necrosis: Cell death.
of cancer.
neoplasia: Abnormal and uncontrolled growth
palliative treatment: Treatment that does not
of cells.
alter the course of a disease, but improves the
quality of life.
neoplasm: An abnormal mass of tissue that
results when cells divide more than they should
penetrance: The likelihood that a given gene
or do not die when they should. Can be benign
will actually result in disease; the proportion of
or malignant.
people with a particular genetic change (such as a
mutation in a specific gene) who exhibit signs and
nevus: Medical term for a benign growth on the
symptoms of a disorder.
skin that is formed by a cluster of melanocytes,
also called a mole.
polyclonal: Population of cells that was derived
by cell division from more than one ancestral cell.
non-Hodgkin lymphoma: One of the several
types of lymphoma (cancer that develops in
polymorphism: A common variation or mutation
the lymphatic system) that are not Hodgkin
in DNA.
lymphoma. Hodgkin lymphoma is rare and
occurs most often in people aged 15 to 40 and in
polyp: A growth that protrudes from a mucous
people over 55. All other lymphomas are grouped
membrane, such as the colon.
together and called non-Hodgkin lymphoma.
precancerous: Term used to describe a condition
nonmelanoma skin cancer: Skin cancer that
that may or is likely to become cancer.
does not involve melanocytes. Basal cell cancer
and squamous cell cancer are nonmelanoma
progesterone: Female hormone produced
skin cancers.
by the ovaries and placenta; responsible for
preparing the uterine lining for implantation
oncogene: A gene that is a mutated form of a gene
of an early embryo.
involved in normal cell growth. Oncogenes may
cause the growth of cancer cells. Mutations in
prognosis: Probable outcome or course of a
genes that become oncogenes can be inherited
disease; the chance of recovery or recurrence.
or caused by being exposed to substances in the
environment that cause cancer.
prophylactic: Treatment administered or taken to
prevent or protect from disease.
oncogenic: Having the capacity to cause cancer.
proto-oncogene: A gene involved in normal cell
oncologist: Doctor who specializes in treating
growth. Mutations (changes) in a proto-oncogene
cancer. Some oncologists specialize in a
may cause it to become an oncogene, which can
particular type of cancer treatment. For
cause the growth of cancer cells.
example, a radiation oncologist specializes
in treating cancer with radiation.
48
radiation therapy: Treatment with high-energy
secondary tumor: A term that is used to describe
rays (such as X-rays) to kill cancer cells and
either a new primary cancer or a metastasis.
shrink tumors. The radiation may come from
outside the body (external radiation) or from
SEER Program: Surveillance, Epidemiology,
radioactive materials placed directly in the tumor
and End Results Program of the National Cancer
(implant radiation). Also called radiotherapy.
Institute. Started in 1973, SEER collects cancer
incidence data in 17 geographic areas covering
radioactive: Giving off radiation.
about 28 percent of the total U.S. population.
radon: Radioactive gas that is released by
side effect: Problem that occurs when treatment
uranium, a substance found in soil and rock.
affects healthy cells. Common side effects of
When too much radon is breathed in, it can
cancer treatment are fatigue, nausea, vomiting,
damage lung cells and lead to lung cancer.
decreased blood cell counts, hair loss, and
mouth sores.
relative risk: Comparison of the risk of
developing cancer in persons with a certain
single-nucleotide polymorphism (SNP): The
type of exposure or characteristic with the risk
most common type of change in DNA (molecules
in persons who do not have this exposure or
inside cells that carry genetic information).
characteristic.
SNPs occur when a single nucleotide (building
block of DNA) is replaced with another. These
remission: Decrease in or disappearance of
changes may cause disease and may affect how
the signs and symptoms of cancer. When this
a person reacts to bacteria, viruses, drugs, and
happens, the disease is said to be “in remission.” A
other substances.
remission can be temporary or permanent.
somatic cell: Any of the body cells except the
retinoblastoma: Eye cancer caused by the loss
reproductive cells.
of both copies of the tumor-suppressor gene RB;
the inherited form typically occurs in childhood