CD20 ;e CD20 protein is found on the surface of nearly
all B cells (see B cell). Its function is not well understood,
but it is a good therapeutic target because it is found on the
surface of the majority of non-Hodgkin lymphomas that
arise from B cells.
Cervical cancer A term for a group of cancers that are
named for the kinds of cells found in the cancer and
by how they look under a microscope. ;e two main
types of cervical cancer are squamous cell carcinoma
and adenocarcinoma. Most cervical cancers are caused
by persistent infection with certain strains of human
papillomavirus (HPV; see Human papillomavirus). Normal
cells of the cervix do not suddenly become cancerous; they
;rst gradually develop precancerous changes, then later
turn into cancer. ;ese changes can be detected by the
Papanicolaou test [see Papanicolaou (Pap) test] and treated
to prevent the development of cancer.
Chemotherapy ;e use of di;erent drugs to kill or slow the
growth of cancer cells.
Chromosome Part of a cell that contains genetic
information. Except for sperm and eggs, all human cells
contain 46 chromosomes.
Chronic lymphocytic leukemia (CLL) ;e most common type
of leukemia diagnosed among adults in the United States.
CLL arises in lymphocytes, most commonly B lymphocytes
(see B cell), in the bone marrow, which then enter the blood.
It is usually slow-growing, but in some people it can be fast-growing.
Clinical trial A type of research study that tests how well
new medical approaches work in people. ;ese studies test
new methods for screening, preventing, diagnosing, or
treating a disease. Also called clinical study.
Colonoscopy Examination of the inside of the colon using a
colonoscope that is inserted into the rectum. A colonoscope
is a thin, tube-like instrument with a light and a lens for
viewing. It may also have a tool to remove tissue to be
checked under a microscope for signs of disease.
Colorectal cancer A group of cancers that start in the colon
or the rectum. More than 95 percent of colorectal cancers
are adenocarcinomas that arise in cells forming glands that
make mucus to lubricate the inside of the colon and rectum.
Before a colorectal cancer develops, a growth of tissue or
tumor usually begins as a noncancerous polyp on the inner
lining of the colon or rectum. Most polyps can be found—
for example, through colonoscopy—and removed before
they turn into cancer.
Computational biology ;e development of data-analytical
and theoretical methods, mathematical modeling, and
computational simulation techniques and their application
to the study of biological, behavioral, and social systems.
Computed tomography (CT) A series of detailed pictures
of areas inside the body taken from di;erent angles. ;e
pictures are created by a computer linked to an X-ray
machine. Also called CAT scan, computerized axial
tomography scan, and computerized tomography.
Cytokine A type of protein that has an e;ect on the immune
system. Some cytokines stimulate the immune system
and others slow it down. Cytokines are o;en produced by
immune cells but can also be produced by nonimmune
cells. ;ey can also be made in the laboratory and used
Cytotoxic chemotherapy Anticancer drugs that kill rapidly
dividing cells, including cancer cells.
Cytotoxic T lymphocyte antigen- 4 (CTLA- 4) A protein on
the surface of immune cells called T cells (see T cell). When
CTLA- 4 attaches to certain proteins on other immune cells,
it sends signals into the T cells to tell them to slow down and
stop acting aggressively. ;us, CTLA- 4 acts as an immune
Death rate/mortality rate ;e number of deaths in a certain
group of people in a certain period of time. Mortality may
be reported for people who have a certain disease; who live
in one area of the country; or who are of a certain gender,
age, or ethnic group.
Deoxyribonucleic acid (DNA) ;e molecules inside cells that
carry genetic information and pass it from one generation
to the next.
Di;use large B-cell lymphoma ;e most common type of
non-Hodgkin lymphoma diagnosed among adults in the
United States. Di;use large B-cell lymphoma is an aggressive
(fast-growing) disease that arises from B cells (see B cell),
which accumulate in the lymph nodes, spleen, liver, bone
marrow, or other organs.
Drug resistance ;e failure of cancer cells, viruses, or
bacteria to respond to a drug used to kill or weaken them.
;e cells, viruses, or bacteria may be resistant to the drug
at the beginning of treatment or may become resistant a;er
being exposed to the drug.
Endpoint In clinical trials, an event or outcome that can be
measured objectively to determine whether the intervention
being studied is bene;cial. ;e endpoints of a clinical trial
are usually included in the study objectives. Some examples
of endpoints are survival, improvements in quality of life,
relief of symptoms, and disappearance of the tumor.
Epigenetics ;e study of heritable changes in gene
expression or cellular phenotype caused by mechanisms
other than changes in DNA sequence. Examples of
such changes might be DNA methylation or histone
deacetylation, both of which serve to suppress gene
expression without altering the sequence of the silenced
Gastric cancer Cancer that arises in cells lining the stomach.
Cancers starting in di;erent sections of the stomach may
cause di;erent symptoms and o;en have di;erent outcomes.
Infection with the bacterium Helicobacter pylori (see
Helicobacter pylori) is a major cause of gastric cancer,
except for gastric cancers arising in the top portion of the
stomach, called the cardia.