Bone Cancer : Risk Factors

Radiotherapy is the use of high-energy penetrating radiation (x rays, gamma rays, proton rays, and neutron rays) to kill cancer cells.

Nonionizing radiation, in contrast to ionizing radiation, is electromagnetic radiation that does not have sufficient energy to remove electrons from an atom or molecules to form an ion (or charged particle) during a collision. Instead, it imparts energy to other particles, which typically results in heating. Nonionizing radiation includes frequencies of the electromagnetic spectrum ranging from 1 hertz (Hz) up to 3×10 10 Hz (300 gigahertz) and its wavelengths range from 10 9 meters down to 10 -7 meters. As the frequency of a wave decreases and the wavelength increases, the energy decreases. Included within this category of nonionizing radiation are—in order of decreasing energy: the lower frequency portion of ultraviolet (UV) radiation, visible light, infrared radiation (IR), microwave radiation, radio frequency radiation, and extremely low frequency (ELF) radiation. Some types of nonionizing radiation have both beneficial and harmful effects on human health. For example, exposure to UV radiation facilitates the synthesis of vitamin D in the human body, and vitamin D plays an important role in intestinal calcium absorption. Lack of vitamin D can result in lead overdosing, kidney damage, and elevated serum cholesterol levels. UV is also used as an antimicrobial agent—it can penetrate food packaging and sterilize the contents—and it is used in tanning beds and salons. On the other hand, acute UV exposure can cause eye and skin damage in humans, and long-term exposure has been found to cause elastosis (loss of skin elasticity) and skin cancer in humans. The sun is the major source of UV radiation. Lasers, one type of nonionizing radiation device that operates at below UV frequencies, are used for a variety of important scientific and industrial processes, but inappropriate exposures can cause severe injuries in humans. Infrared radiation, which can be used in home electrical appliances, welding, furnaces, and foundries, can cause skin and eye damage through excessive heating. Lower-frequency nonionizing radiation, such as microwave, radio frequency, and ELF radiation, have many beneficial uses—such as tracking radar, weather radar, microwave ovens, radio navigation, satellite communication, broadcast radio and television, and a variety of other communications devices including two-way radios and cellular phones. Acute effects from direct exposure to high levels of this type of radiation can include severe burns, electric shocks, and even death. The human health effects of chronic exposure to these types of radiation are less clear. The higher frequencies in this range, such as microwaves, may cause adverse heating effects. The majority of studies, which have focused on exposure to ELF radiation, have examined cancer, adverse reproductive outcomes, neurodegenerative diseases, and cardiac abnormalities. However, difficulties in conducting these studies, including defining and measuring the biologically relevant exposure and variation in subjects' responses, have left substantial uncertainty. The most effective means of preventing exposure to most types of nonionizing radiation is to maintain a safe distance from the source. Other means of preventing or limiting exposure, such as using shields, are far more difficult and costly, particularly as the size of the source increases. Unlike ionizing radiation, nonionizing radiation penetrates through most materials relatively unchanged. Special metallic grids can be designed to exclude radiation of particular frequencies, but this is not currently practical, physically, for handheld devices such as cellular phones and two-way radios, and is very onerous for large-scale implementation, such as around houses or buildings. D ANIEL W ARTENBERG ( SEE ALSO : Electromagnetic Fields ; Radiation, Ionizing )

Electromagnetic waves of extremely short wavelength (X-rays and gamma rays) and accelerated atomic particles (such as electrons, protons, neutrons, and alpha particles) deposit enough localized energy in an absorbing medium to dislodge electrons from atoms with which they interact and to disrupt chemical bonds. The loss of electrons creates particles known as "ions," and these types of radiation are termed "ionizing radiation." Natural sources of such radiation, which are ubiquitous and to which all people are exposed, include cosmic rays, radioactive elements in the earth's crust, internally deposited radionuclides, and inhaled radon. Artificial sources include the use of X-rays in medical and dental diagnosis; radioactive materials in building materials, phosphate fertilizers, and crushed rock; radiation-emitting components of TV sets, smoke detectors, and other consumer products; radioactive fallout from atomic weapons; and nuclear power. Additional sources are encountered by workers in certain workplace environments. As ionizing radiation penetrates a living cell, it collides randomly with atoms and molecules in its path, giving rise to ions, free radicals, and other molecular alterations that may injure the cell. Any molecule in the cell can be altered by radiation, but DNA is the most critical biological target because of the limited redundancy of the genetic information it contains. A dose of radiation that is large enough to kill the average dividing cell causes hundreds of lesions in the cell's DNA molecules. Most such lesions are reparable, but those produced by a densely ionizing radiation (such as a proton or an alpha particle) are generally more complex and less reparable than those produced by a sparsely ionizing radiation (such as an X-ray or a gamma ray). Any damage to DNA that remains unrepaired or is improperly repaired may result in a mutation or chromosome aberration, and both of these types of effects appear to rise in frequency in proportion to any increase in the dose in the low-dose domain. Damage to the genetic apparatus may be lethal to cells, especially dividing cells—the depletion of which in a given organ may cause severe damage. In radiation accident victims, for example, the depletion of blood-forming cells in the bone marrow is typically a cause of early death. Although the production of an overt clinical reaction generally requires a dose that is large enough to kill many cells, smaller doses can suffice to cause malformations and other disturbances of development in an embryo. Although adverse health effects have not been demonstrated at the low exposure levels characteristically associated with natural background irradiation, it is noteworthy that at higher dose levels many of the cellular alterations that are precursors to cancer, as well as the risks of some forms of cancer themselves, appear to increase in frequency as linear-nonthreshold functions of the dose. The risks to human health and to the environment from exposure to ionizing radiation have been reviewed repeatedly by the National Research Council, the National Council on Radiation Protection and Measurements, the International Commission on Radiological Protection, the United Nations Scientific Committee on the Effects of Atomic Radiation, and various other national and international organizations. Such organizations have generally concurred in the conclusion that the existence of a threshold for risks in the low-dose domain cannot be excluded, but that the weight of existing evidence supports the hypothesis that the genetic and carcinogenic effects of radiation increase in frequency as linear-nonthreshold functions of the dose. Assessments of the risks of low-level radiation for public health purposes are, therefore, generally based on the use of linear-nonthreshold dose-response models, their inherent uncertainties notwithstanding. In other words, there is an assumption that there is no threshold for the cancer-causing ef

Radiation and radioisotopes are extensively used medications to allow physicians to image internal structures and processes in vivo (in the living body) with a minimum of invasion to the patient. Higher doses of radiation are also used as means to kill cancerous cells. Radiation is actually a term that includes a variety of different physical phenomena. However, in essence, all these phenomena can be divided into two classes: phenomena connected with nuclear radioactive processes are one class, the so-called radioactive radiation (RR); electromagnetic radiation (EMR) may be considered as the second class. Both classes of radiation are used in diagnoses and treatment of neurological disorders.

The principal adverse health effects of sunlight are caused by the ultraviolet and visible radiation it contains. Ultraviolet radiation (UVR) comprises a spectrum of electromagnetic waves of different wavelengths, subdivided for convenience into three bands, which are measured in nanometers (nm):(1) UVA ("black light"), 315 to 400 nm; (2) UVB, 280 to 315 nm; and (3) UVC (which is germicidal), 200 to 280 nm. Visible light consists of electromagnetic waves varying in wavelength from about 400 (violet) to 700 nm (red). None of these radiations penetrates deeply into human tissue, so that the injuries they cause are confined chiefly to the skin and eyes. Reactions of the skin to UVR are common among fair-skinned people and include sunburn, skin cancers (basal cell and squamuous cell carcinomas, and to a lesser extent melanomas), aging of the skin, solar elastoses, and solar keratoses. Injuries of the eye include photokeratitis, which may result from prolonged exposure to intense sunlight ("snow blindness"); photochemical blue-light injury of the retina, from gazing directly at the sun; cortical cataract of the lens; and uveal melanoma. The effects of UVR result chiefly from its absorption in DNA, resulting in the cross-linkage of pyriminide nucleotides, which, in turn, may cause mutations in exposed cells. Sensitivity to UVR may be decreased by DNA repair defects, by agents that inhibit the repair enzymes, and by photosensitizing agents (such as psoralens, sulfonamides, tetracyclines, and coal tar) that increase the absorption of UVR in DNA. To prevent injury by sunlight, excessive exposure to the sun should be avoided—especially by fair-skinned individuals—and protective clothing, UVR-screening lotions or creams, and UVR-blocking sunglasses should be used when necessary. Also, although the sun is unlikely to cause a retinal burn under normal viewing conditions since bright, continuously visible light normally elicits an aversion response that acts to protect the eye against injury, one must never gaze at the sun nor look directly at a solar eclipse. From an environmental perspective, it is noteworthy that the protective layer of ozone in the stratosphere is gradually being depleted by chlorofluorocarbons and other air pollutants, and that every 1 percent decrease in stratosphereic ozone shield is expected to raise the UVR reaching the earth sufficiently to increase the frequency of skin cancer by 2 to 6 percent. Of potentially greater significance for human health than the projected increase in cancer rates, however, are the farreaching impacts on vegetation and crop production that may result from depletion of the ozone shield. A RTHUR C. U PTON

What kind of radiation causes thyroid cancer? What about microwave ovens and dental x-rays?

Can a breast that has undergone radiation treatment for cancer be biopsied in the future, if necessary?

Can radiation treatments for prostate cancer damage the bladder, causing it to bleed 10 years after the radiation?

According to recent reports, the radiation used during a heart stress test can set off security alarms used in buildings and airports.

Treating Bladder Cancer: RadiationRadiation is a way of treating cancer. Radiation uses beams of energy to destroy cancer cells.

My father had a pacemaker implanted five years ago. He wants to purchase a new 5.8 GHz cordless phone. I have heard the cellular phones have had some interference with pacemakers; is this also true of digital cordless phones at this frequency?

Li-Fraumeni syndrome (LFS) is a hereditary condition in which individuals have an increased risk for developing certain kinds of tumors. The characteristic tumors of LFS are adrenocortical carcinoma, breast cancer , brain cancer , leukemia, and sarcoma. Li-Fraumeni syndrome has previously been known as the Sarcoma, Breast, Leukemia and Adrenal gland (SBLA) syndrome.

Detailed information on Li-Fraumeni syndrome, including causes of the disorder

Li-Fraumeni syndrome (LFS) is a hereditary condition in which individuals have an increased risk for developing certain kinds of tumors. The characteristic tumors of LFS are adrenocortical carcinoma, breast cancer , brain cancer, leukemia and sarcoma. Li-Fraumeni syndrome has previously been known as the sarcoma, breast, leukemia and adrenal gland (SBLA) syndrome.

Li-Fraumeni syndrome (LFS) is a genetic disorder caused by a hereditary mutation in a cancer susceptibility gene. Individuals with LFS have an increased risk for developing certain types of cancer, often at younger ages than is typically observed in the general population.

Detailed information on osteochondroma, including causes, symptoms, diagnosis, and treatment

Hereditary multiple exostoses (HME) refers to a group of disorders characterized by abnormal bone growth. The major symptom is the development of nodules (bumps) on various bones of the body. Exostoses may produce pain and other complications by pressing on nearby tissue, they may limit movement of joints, and in some cases they must be surgically removed.

Hereditary multiple exostoses (HME) refers to a group of disorders characterized by abnormal bone growth. The major symptom is the development of nodules (bumps) on various bones of the body. Exostoses may produce pain and other complications by pressing on nearby tissue, they may limit movement of joints, and in some cases they must be surgically removed.

Retinoblastoma is a malignant tumor of the retina that occurs predominantly in young children.

Retinoblastoma is a malignant tumor (cancer) of the retina (part of the eye) that generally affects children under the age of 6. It is most commonly diagnosed in children aged 1 - 2 years.

RetinoblastomaDescriptionWhat is retinoblastoma?Retinoblastoma is a malignant (cancerous) tumor of the retina.

Paget's disease of bone ( osteitis deformans ) is the abnormal formation of bone tissue that results in weakened and deformed bones.

Paget's disease is a disorder that involves abnormal bone destruction and regrowth, which results in deformity.

Detailed information on Paget's disease of the bone, including causes, symptoms, diagnosis, and treatment

Detailed information on Paget's disease of the bone, including causes, symptoms, diagnosis, and treatment

Detailed information on Kaposi's sarcoma and Paget's disease of the skin

Rothmund-Thomson syndrome (RTS) is an extremely rare inherited disorder that appears in infancy and features skin degeneration (atrophic dermatosis), clouding of the lenses of the eyes (juvenile cataracts), skeletal abnormalities, short stature, and an increased risk of skin and bone cancers.

Rothmund-Thomson syndrome (RTS) is an extremely rare inherited disorder that appears in infancy and features skin degeneration (atrophic dermatosis), clouding of the lenses of the eyes (juvenile cataracts), skeletal abnormalities, short stature, and an increased risk of skin and bone cancers.