Glossary O

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oblique: a plane or section not perpendicular to the xyz coordinate system, such as long and short axis views of the heart

occult: detectable only by microscopic examination or chemical analysis, as a minute blood sample 

octreotide (Sandostatin®): a synthetic protein that is similar to the naturally-occurring hormone called somatostatin. Octreotide decreases the production of many substances in the body such as insulin and glucagon (involved in regulating blood sugar), growth hormone, and chemicals that affect digestion.

ODC: ornithine decarboxylase; a rate-limiting enzyme in the pathway of mammalian polyamine biosynthesis. Polyamines affect DNA, RNA and protein synthesis.  For these reasons, ODC activity is said to be closely associated with tumor promotion. Green tea polyphenols inhibit ODC resulting in a decrease in polyamine synthesis and cell growth. 

omega 3 fatty acids: are nutritional elements essential to human health which cannot be produced by the body. They can be found in fish and other marine life. Also known as polyunsaturated fatty acids

oncogene: a gene having the potential to cause (or facilitate) a normal cell to become cancerous

oncogenesis: the process of cellular changes leading to the formation of a malignant tumor

oncologist: a physician who specializes in the treatment of various types of cancer

oncology: the branch of medical science dealing with tumors; an oncologist is a specialists in the study of cancerous tumors

oncolytic virus: a virus that causes death of a tumor cell; after the Greek word onkos for tumor or mass

opioid: originally, a term denoting synthetic narcotics resembling opiates, but increasingly used to refer to both opiates and synthetic narcotics

orchiectomy (orchidectomy): the surgical removal of the testicles; surgical castration

organ: a group of tissues that work in concert to carry out a specific set of functions (e.g., the heart or the lungs or the prostate)

organ confined disease (OCD): PC that is apparently confined to the prostate clinically or pathologically; not going beyond the confines of the prostatic capsule

organism: any individual living animal or plant

orgasm: the highest point of sexual excitement, characterized by strong feelings of pleasure and marked normally by ejaculation of semen by the male and by vaginal contractions in the female; also called climax

orphan drug: a category created by US FDA for medications used to treat diseases that occur rarely (less than 200,000 cases) or that there is no hope for recovery of development costs, so there is little financial incentive for industry to develop them; orphan drug status gives the manufacturer financial incentives to provide the drug

orthotopic: in the normal or usual position

osseous: consisting of or resembling bone

osteoarthritis: noninflammatory degenerative joint disease occurring chiefly in older persons characterized by changes in the bone and cartilage the joints and a progressive wearing down of joint surfaces

osteoblast: cell that forms bone

osteoclast: cell that breaks down bone; osteoclasts are in bone tissue and resorb bone leading to bone loss or osteopenia or osteoporosis

osteoid: uncalcified bone matrix, the product of osteoblasts. Consists mainly of collagen

osteolysis: destruction of bone

osteonecrosis: condition resulting in death of bone tissue

osteopenia: a reduction in the bone density that is more than one standard deviation from the normal bone density; using the T score it is T=-1.0 down to T= -2.4; once the T score is less than 2.4, the patient is defined as having osteoporosis

osteoporosis: a reduction in bone density resulting in a T score of -2.5 or less; a loss of bone due to increased osteoclastic activity leading to bone resorption

overexpress: produce in excess, as does the genetic material of cancer cells

overstaging: the assignment of an overly high clinical stage at initial diagnosis because of the difficulty of  assessing the available information with accuracy (e.g., stage T3b as opposed to stage T2b)

oxidant: a substance that causes another substance to combine with oxygen

oxidation: a process where the amount of oxygen of a chemical compound is increased