C

Calcifications: Small calcium deposits in the breast, singly or in clusters, often found by mammography. Also called microcalcifications. They signal changes in the breast that may need to be followed by more mammograms, or a biopsy. They may be caused by breast cancer or by benign breast conditions.

Cancer: A group of diseases in which all forms cause cells to change and grow out of control. Most cancers form a lump or mass called a tumor. Tumors can invade and destroy healthy tissue. Tumor cells can break away and travel to other parts of the body. There they can continue to grow. This spreading is called metastasis. When cancer spreads, it is named after the part of the body in which it started. If breast cancer spreads to the lungs, it is still called breast cancer, not lung cancer. Some cancers, such as blood cancers, do not form tumors. Not all tumors are cancerous. A non-cancerous tumor is called benign. Benign tumors do not grow and spread the way cancer does. Benign turmors are usually not life threatening. Another word for cancerous is malignant.

Cancer care team: Group of health care professionals who work together to diagnose, treat, and care for cancer patients. The team may include: primary care physicians, pathologists, oncology specialists such as medical or radiation oncologists, surgeons including surgical specialists such as urologists, gynecologists, neurosurgeons, etc., nurses, oncology nurse specialists, oncology social workers and others. Usually one person takes the job of coordinating the team, which can be a formal or informally organized group.

Cancer cell: Cell that divides and reproduces abnormally with the potential to spread throughout the body, crowding out normal cells and tissue.

Cancer susceptibility genes: Genes inherited from one's parents that greatly increase the risk of a person's developing cancer. About 5%-15% of all cancers are linked to these genes.

Cancer vaccine: Used in treatments (not prevention) of some cancers, it is made from pieces of tumors and works by causing the immune system to recognize and attack cancer cells. Intense research is underway in this area...including research for a vaccine to prevent cancer.

Carcinoembryonic antigen: Substance normally found in fetal tissue that, if found in an adult, may signal a cancer is present, especially one starting in the digestive system. Tests for this substance may help determine if a colorectal cancer has recurred after treatment.

Carcinogen: Any chemical, physical or viral agent that causes cancer such as tobacco smoke or asbestos.

Carcinoma: Malignant (cancerous) tumor that begins in the lining layer (epithelial cells) of organs. At least 80% of all cancers are carcinomas.

Carcinoma in situ: Early stage cancer in which tumors are confined to the organ where they first started and have not invaded other parts of the organ or spread to distant parts of the body. Most in situ carcinomas are highly curable.

Case manager: The member of a cancer care team, usually a nurse or oncology nurse specialist, who coordinates patient care throughout diagnosis, treatment, and recovery. The case manager helps cut through red tape, gets responses to questions, manages crises, and connects the patient and family to needed resources.

Catheter: Thin, flexible tube through which fluids enter or leave the body; e.g., a tube to drain urine.

cDNA: See complementary DNA.

CEA: (See: Carcinoembryonicantigen.)

Cell: Basic unit of which all living things are made. Cells replace themselves by dividing and forming new cells (mitosis).

Cell cycle: The steps a cell goes through to divide; some chemotherapy drugs act by interfering with this cycle.

Centimorgan (cM): A unit of measure of recombination frequency. One centimorgan is equal to a 1% chance that a marker at one genetic locus will be separated from a marker at a second locus due to crossing over in a single generation. In human beings, one centimorgan is equivalent, on average, to one million base pairs.

Centromere: A specialized chromosome region to which spindle fibers attach during cell division.

Cervix: The neck of the womb (uterus).

Chemoprevention: Prevention or reversal of disease using drugs, chemicals, vitamins, or minerals. While this idea is not ready for widespread use, it is a very promising area of study. The Breast Cancer Prevention Trial has shown that the drug tamoxifen can prevent some cases of breast cancer among women with high risk of the disease. But the drug may have some serious side effects.

Chemotherapy: Drug treatments used to destroy cancer cells. Often used with surgery or radiation to treat cancer when the cancer has spread, when it has come back (recurred), or when there is a strong chance that it could recur.

Chromosome: Chromosomes carry the genes, the basic units of heredity. Humans have 23 pairs of chromosomes, one member of each pair from the mother, the other from the father. Each chromosome can contain hundreds or thousands of individual genes. Chromosomes are the self-replicating genetic structure of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryotic genomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins.

Clinical breast exam: An examination of the breasts done by a health professional such as a doctor or nurse.

Clinical trials : Studies of new treatments in patients who volunteer to participate. A clinical trial is only done when there is some reason to believe that the treatment being studied may be of value to the patient. The main questions the researchers want to answer are:
Does this treatment work or work better than those now in use?
What side effects does it cause?
Do the benefits outweigh the risks? 
Which patients are most likely to benefit?
If you elect to participate in a trial, particularly a drug trial, you may or may not receive the drug actually being tested. You may be given a "sugar pill" in so-called double-blind tests in which some participants are given the experimental drug and a control group is given a placebo (sugar pill). To measure the effectiveness of the experimental drug, the outcomes of the two groups are closely tracked.

Clone bank: See genomic libary.

Clone: An exact copy made of biological material such as a DNA segment (a gene or other region), a whole cell, or a complete organism.

Cloning: Using specialized DNA technology (see cloning vector) to produce multiple, exact copies of a single gene or other segment of DNA to obtain enough material for further study. This process is used by researchers in the Human Genome Project, and is referred to as cloning DNA. The resulting cloned (copied) collections of DNA molecules are called clone libraries. A second type of cloning exploits the natural process of cell division to make many copies of an entire cell. The genetic makeup of these cloned cells, called a cell line, is identical to the original cell. A third type of cloning produces complete, genetically identical animals such as the famous Scottish sheep, Dolly.

Cloning vector: DNA molecule originating from a virus, a plasmid, or the cell of a higher organism into which another DNA fragment of appropriate size can be integrated without loss of the vectors capacity for selfreplication; vectors introduce foreign DNA into host cells, where it can be reproduced in large quantities. Examples are plasmids, cosmids, and yeast artificial chromosomes; vectors are often recombinant molecules containing DNA sequences from several sources.

cM: See centimorgan.

Code: See genetic code

Codon: See genetic code

Colectomy: Removal of all (total) or part (partial colectomy or hemicolectomy, for example) of the colon.

Colon: Large intestine - a muscular tube about 5 feet long.

Colonoscope: Slender, flexible, hollow lighted tube about half inch thick is inserted through the rectum into the colon. A colonoscope is much longer than a sigmoidoscope, and allows the doctor to see much more of the colon's lining. The colonoscope is connected to a video camera and video display monitor so the doctor can look closely at the inside of the colon.

Colonoscopy: Examination of the colon with a long, flexible, lighted tube called a colonoscope.

Colony stimulating factors (CSF): Growth factors that promote growth and division of blood-producing cells in the bone marrow. CSFs are naturally produced in the body but extra amounts may be given as a treatment to reduce or prevent certain side effects of chemotherapy due to not having enough blood cells.

Colorectal: Pertaining to the colon (large intestine, which is about 59 inches long and the rectum.

Colostomy: Opening in the abdomen for expelling body waste (stool). A colostomy is sometimes needed after surgery for cancer of the rectum.

Combined modality therapy: Two or more treatment types used alternately or together to get the better results. For example, surgery for cancer is often followed by chemotherapy to destroy cancer cells that may have spread from the original site.

Complementary therapy: Therapies used in addition to a standard therapy. Some complementary therapies may help relieve certain symptoms of cancer, relieve side effects of standard cancer therapy, or improve a patient's sense of well-being. The American Cancer Society recommends that patients considering use of any alternative or complementary therapy discuss this with their health care team. See also, alternative therapy.

Complementary DNA (cDNA): DNA that is synthesized from a messenger RNA template; the single-stranded form is often used as a probe in physical mapping.

Complementary sequence: Nucleic acid base sequence that can form a doublestranded structure by matching base pairs with another sequence; the complementary sequence to GTAC is CATG.

Computed tomography: Imaging test in which many x-rays are taken from different angles of a part of the body. The images are combined by computer to produce cross-sectional pictures of organs. Except for the injection of a dye (needed in some but not all cases), this is a painless procedure that can be done in an outpatient clinic. Often referred to as a "CT" or "CAT" scan.

Conserved sequence: A base sequence in a DNA molecule (or an amino acid sequence in a protein) that has remained essentially unchanged throughout evolution.

Contig: Group of cloned (copied) pieces of DNA representing overlapping regions of a particular chromosome.

Contig map: A map depicting the relative order of a linked library of small overlapping clones representing a complete chromosomal segment.

Continent urostomy : Surgical diversion of urine through a new passage and then through an opening in the abdomen. In a continent urostomy, urine is stored inside the body and drained a few times a day through a tube placed into an opening called a stoma.

Corticosteroid: Any of numerous steroid substances obtained from the cortex of the adrenal glands. They are sometimes used as an anti-cancer treatment.

Cosmid: Artificially constructed cloning vector containing the cos gene of phage lambda. Cosmids can be packaged in lambda phage particles for infection into E. coli; this permits cloning of larger DNA fragments (up to 45kb) than can be introduced into bacterial hosts in plasmid vectors.

Crohn's disease: A chronic inflammatory bowel disease in which the small bowel and, less often, the colon is inflamed over a long period of time. This increases a person's risk of developing colon cancer, so starting colorectal cancer screening earlier and doing such tests more often is recommended.

Crossing over: The breaking during meiosis of one maternal and one paternal chromosome, the exchange of corresponding sections of DNA, and the rejoining of the chromosomes. This process can result in an exchange of alleles between chromosomes. Compare recombination.

Cryoablation: Using extreme cold to freeze and destroy cancer cells.

Cryosurgery: (See: Cryoablation.)

CT scan: (See: Computed tomography.)

Cyst: Fluid-filled mass - usually benign. The fluid can be removed for analysis. (See: Needle aspiration.)

Cystoscopy: Bladder exam with an instrument called a cystoscope.

Cytokine: A product of immune system cell that may stimulate immunity and cause the regression of some cancers.

Cytology: Branch of science dealing with the structure and function of cells. Also refers to tests to diagnose cancer and other diseases by examining cells under the microscope.

Cytometry: Counting and measuring of cells using a machine called a flow cytometer.

Cytosine (C): A nitrogenous base, one member of the base pair GC (guanine and cytosine).

Cytotoxic: Toxic to cells; cell-killing.