How common is lung cancer?

Lung cancer is the most common cause of death due to cancer in both men and women throughout the world. The American Cancer Society estimates that 219,440 new cases of lung cancer in the U.S. will be diagnosed and 159,390 deaths due to lung cancer will occur in 2009. According to the U.S. National Cancer Institute, approximately one out of every 14 men and women in the U.S. will be diagnosed with cancer of the lung at some point in their lifetime.

Lung cancer is predominantly a disease of the elderly; almost 70% of people diagnosed with lung cancer are over 65 years of age, while less than 3% of lung cancers occur in people under 45 years of age.

Lung cancer was not common prior to the 1930s but increased dramatically over the following decades as tobacco smoking increased. In many developing countries, the incidence of lung cancer is beginning to fall following public education about the dangers of cigarette smoking and the introduction of effective smoking-cessation programs. Nevertheless, lung cancer remains among the most common types of cancers in both men and women worldwide. In the U.S., lung cancer has surpassed breast cancer as the most common cause of cancer-related deaths in women.

What causes lung cancer?

Smoking

The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use. The risk of lung cancer increases with the number of cigarettes smoked and the time over which smoking has occurred; doctors refer to this risk in terms of pack-years of smoking history (the number of packs of cigarettes smoked per day multiplied by the number of years smoked). For example, a person who has smoked two packs of cigarettes per day for 10 years has a 20 pack-year smoking history. While the risk of lung cancer is increased with even a 10-pack-year smoking history, those with 30-pack-year histories or more are considered to have the greatest risk for the development of lung cancer. Among those who smoke two or more packs of cigarettes per day, one in seven will die of lung cancer.

Pipe and cigar smoking also can cause lung cancer, although the risk is not as high as with cigarette smoking. Thus, while someone who smokes one pack of cigarettes per day has a risk for the development of lung cancer that is 25 times higher than a nonsmoker, pipe and cigar smokers have a risk of lung cancer that is about five times that of a nonsmoker.

Tobacco smoke contains over 4,000 chemical compounds, many of which have been shown to be cancer-causing or carcinogenic. The two primary carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons. The risk of developing lung cancer decreases each year following smoking cessation as normal cells grow and replace damaged cells in the lung. In former smokers, the risk of developing lung cancer begins to approach that of a nonsmoker about 15 years after cessation of smoking.

Passive smoking

Passive smoking or the inhalation of tobacco smoke by nonsmokers who share living or working quarters with smokers, also is an established risk factor for the development of lung cancer. Research has shown that nonsmokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with nonsmokers who do not reside with a smoker. An estimated 3,000 lung cancer deaths that occur each year in the U.S. are attributable to passive smoking.

Asbestos fibers

Asbestos fibers are silicate fibers that can persist for a lifetime in lung tissue following exposure to asbestos. The workplace is a common source of exposure to asbestos fibers, as asbestos was widely used in the past as both thermal and acoustic insulation. Today, asbestos use is limited or banned in many countries, including the U.S. Both lung cancer and mesothelioma (cancer of the pleura of the lung as well as of the lining of the abdominal cavity called the peritoneum) are associated with exposure to asbestos. Cigarette smoking drastically increases the chance of developing an asbestos-related lung cancer in workers exposed to asbestos. Asbestos workers who do not smoke have a fivefold greater risk of developing lung cancer than nonsmokers, but asbestos workers who smoke have a risk that is 50- to 90-fold greater than nonsmokers.

Radon gas

Radon gas is a natural, chemically inert gas that is a natural decay product of uranium. Uranium decays to form products, including radon, that emit a type of ionizing radiation. Radon gas is a known cause of lung cancer, with an estimated 12% of lung-cancer deaths attributable to radon gas, or about 20,000 lung-cancer-related deaths annually in the U.S., making radon the second leading cause of lung cancer in the U.S. As with asbestos exposure, concomitant smoking greatly increases the risk of lung cancer with radon exposure. Radon gas can travel up through soil and enter homes through gaps in the foundation, pipes, drains, or other openings. The U.S. Environmental Protection Agency estimates that one out of every 15 homes in the U.S. contains dangerous levels of radon gas. Radon gas is invisible and odorless, but it can be detected with simple test kits.

Familial predisposition

While the majority of lung cancers are associated with tobacco smoking, the fact that not all smokers eventually develop lung cancer suggests that other factors, such as individual genetic susceptibility, may play a role in the causation of lung cancer. Numerous studies have shown that lung cancer is more likely to occur in both smoking and non-smoking relatives of those who have had lung cancer than in the general population. Recently, the largest genetic study of lung cancer ever conducted, involving over 10,000 people from 18 countries and led by the International Agency for Research on Cancer (IARC), identified a small region in the genome (DNA) that contains genes that appear to confer an increased susceptibility to lung cancer in smokers. The specific genes, located the q arm of chromosome 15, code for proteins that interact with nicotine and other tobacco toxins (nicotinic acetylcholine receptor genes).

Lung diseases

The presence of certain diseases of the lung, notably chronic obstructive pulmonary disease (COPD), is associated with an increased risk (four- to sixfold the risk of a nonsmoker) for the development of lung cancer even after the effects of concomitant cigarette smoking are excluded.

Prior history of lung cancer

Survivors of lung cancer have a greater risk of developing a second lung cancer than the general population has of developing a first lung cancer. Survivors of non-small cell lung cancers (NSCLCs, see below) have an additive risk of 1%-2% per year for developing a second lung cancer. In survivors of small cell lung cancers (SCLCs, see below), the risk for development of second lung cancers approaches 6% per year.

Air pollution

Air pollution from vehicles, industry, and power plants can raise the likelihood of developing lung cancer in exposed individuals. Up to 1% of lung cancer deaths are attributable to breathing polluted air, and experts believe that prolonged exposure to highly polluted air can carry a risk for the development of lung cancer similar to that of passive smoking.

What Is Stroke?

What is a stroke?

A stroke occurs when a blood vessel in the brain is blocked or bursts. Without blood and the oxygen it carries, part of the brain starts to die. The part of the body controlled by the damaged area of the brain can't work properly.

Brain damage can begin within minutes, so it is important to know the symptoms of stroke and act fast. Quick treatment can help limit damage to the brain and increase the chance of a full recovery.
What are the symptoms?

Symptoms of a stroke happen quickly. A stroke may cause:

    * Sudden numbness, tingling, weakness, or paralysis in your face, arm, or leg, especially on only one side of your body.
    * Sudden vision changes.
    * Sudden trouble speaking.
    * Sudden confusion or trouble understanding simple statements.
    * Sudden problems with walking or balance.
    * A sudden, severe headache that is different from past headaches.

If you have any of these symptoms, call911or other emergency services right away.

See your doctor if you have symptoms that seem like a stroke, even if they go away quickly. You may have had a transient ischemic attack (TIA), sometimes called a mini-stroke. A TIA is a warning that a stroke may happen soon. Getting early treatment for a TIA can help prevent a stroke.
What causes a stroke?

There are two types of stroke:

    * An ischemic stroke develops when a blood clot blocks a blood vessel in the brain. The clot may form in the blood vessel or travel from somewhere else in the blood system. About 8 out of 10 strokes are ischemic (say "iss-KEE-mick") strokes. They are the most common type of stroke in older adults.
    * A hemorrhagic stroke develops when an artery in the brain leaks or bursts. This causes bleeding inside the brain or near the surface of the brain. Hemorrhagic (say "heh-muh-RAH-jick") strokes are less common but more deadly than ischemic strokes.

How is a stroke diagnosed?

You need to see a doctor right away. If a stroke is diagnosed quickly-right after symptoms start-doctors may be able to use medicines that can help you recover better.

The first thing the doctor needs to find out is what kind of stroke it is: ischemic or hemorrhagic. This is important because the medicine given to treat a stroke caused by a blood clot could be deadly if used for a stroke caused by bleeding in the brain.

To find out what kind of stroke it is, the doctor will do a type of X-ray called a CT scan of the brain, which can show if there is bleeding. The doctor may order other tests to find the location of the clot or bleeding, check for the amount of brain damage, and check for other conditions that can cause symptoms similar to a stroke.

What Increases Your Risk

Risk factors for stroke include those you can change and those you can't change.

Certain diseases or conditions increase your risk of stroke. These include:

* High blood pressure (hypertension). High blood pressure is the second most important stroke risk factor after age. It is a risk factor you can change.

* Diabetes. Having diabetes doubles your risk of stroke because of the circulation problems associated with the disease.

* High cholesterol. High cholesterol can lead to hardening of your arteries (atherosclerosis). Hardening of the arteries can cause coronary artery disease and heart attack, which can damage the heart muscle and increase your risk for stroke.

* Coronary artery disease, which can lead to heart attack and stroke.

* Other heart conditions, such as atrial fibrillation, endocarditis, heart valve conditions, patent foramen ovale, or heart failure.

* Peripheral arterial disease, for example narrowing of the carotid artery (carotid artery stenosis).

Certain behaviors can increase your risk of stroke. These include:

* Smoking, including secondhand smoke.

* Physical inactivity.

* Being overweight.

* Diet with few fruits and vegetables. Research suggests that people who eat more fruits, vegetables, fish, and whole grains (for example, brown rice) may have a lower risk of stroke than people who eat lots of red meat, processed foods such as lunch meat, and refined grains (for example, white flour).2

* Diet with too much salt. A healthy diet includes less than 2,300 mg of sodium a day (about one teaspoon).

* Use of some medicines, such as birth control pills-especially by women who smoke or have a history of blood-clotting problems. In postmenopausal women, hormone replacement therapy has been shown to slightly increase the risk of stroke.3

* Heavy use of alcohol. People who drink alcohol excessively, especially people who binge drink, are more likely to have a stroke. Binge drinking is defined as drinking more than 5 drinks in a short period of time.

* Illegal drug use (such as a stimulant, like cocaine).

Risk factors you cannot change include:

* Age. The risk of stroke increases with age.

* Race. African Americans, Native Americans, and Alaskan Natives have a higher risk than those of other races. Compared with whites, African Americans have about 2 times the risk of a first ischemic stroke. And African-American men and women are more likely to die from stroke.4

* Gender. Stroke is more common in men than women until age 75, when more women than men have strokes. Because women live longer than men, more women than men die of stroke.4

* Family history. The risk for stroke is greater if a parent, brother, or sister has had a stroke or transient ischemic attack (TIA). For more information, see the topic Transient Ischemic Attack (TIA).

* History of stroke or TIA.

Diagnosing menopause

Diagnosis & Tests


Diagnosing menopause isn't always easy. Learn about how menopause is sometimes diagnosed, and about tests you'll want to take as your body changes.
Diagnosis
Diagnosing Menopause

How do you know you're entering menopause? Are there tests that diagnose menopause? Find out here.
Tests
Home Menopause Testing Kits: Are They Worth It?

Home menopause test kits help you measure your body's follicle-stimulating hormone (FSH) levels, with the goal of helping you check for symptoms of perimenopause and menopause. Do they work? One expert tells why she doesn't think so.
Related Guide: Menopause and FSH Tests

A follicle stimulating hormone (FSH) test measures the amount of FSH in a woman's blood and may help determine whether she has gone through menopause. Learn more in this in-depth article.
Related Web Site: Evaluation of Premature Ovarian Failure

See what needs to be looked at and why if you have early menopause. This link will take you to another site.
Bone Mineral Density Testing During Menopause

Your osteoporosis risks increase after menopause. A bone mineral density test, or bone densitometry, can quickly measure the amount of calcium in your bones. Find out why you need this test, how to prepare for it, and the several ways it can be performed.
Breast Self-exam and Menopause

Age increases our breast cancer risks. The most effective way to fight breast cancer is to detect it early, through breast self-exams and mammograms. This article offers easy-to-follow tips on performing a breast self-exam.
Menopause and Mammogram Testing

Breast cancer risks increase as we age, so the best way to fight back is through early detection via mammograms and breast self-exams. Mammography uses special X-ray images to detect changes in breast tissue. Learn how to prepare for a mammogram, how often to get one, and what happens after the test.
Why Do You Need a Pelvic Exam?

The risk of cancer increases with age, so regular pelvic exams may help in early detection of certain cancers like ovarian cancer. Find out how often you need a pelvic exam, how the test is performed, and what other tests may be taken at the same time.
Menopause and Pap Tests

A pap smear is your best tool to detect precancerous conditions and hidden tumors that may lead to cervical cancer. How often should you have a pap smear after menopause? What symptoms should you watch for between tests? Learn here.

Study Suggests Exposure to Chemicals Called PFCs May Be Associated With Earlier Menopause

Women exposed to high levels of chemicals called perfluorocarbons (PFCs) may enter menopause earlier, new research suggests.

PFCs are man-made chemicals found in many household products such as food containers and stain-resistant clothing as well as in water, soil, and plants.

''Before this study, there was strong evidence from animal research that PFCs were endocrine disruptors," says researcher Sarah Knox, PhD, professor of epidemiology at the West Virginia University School of Medicine, Morgantown.

For the study, she evaluated the levels of two PFCs, called PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoate) in nearly 26,000 women, ages 18 to 65.

Overall, she found, ''the higher the perfluorocarbons, the earlier the menopause." Women between ages 42 and 64 with the highest blood levels of the PFCs were more likely to have experienced menopause than those with the lowest levels.

One of the chemicals, PFOS, affected levels of the hormone estradiol, a form of estrogen. "The higher the levels of PFOS, the lower the levels of estradiol," she says. As estradiol declines, menopause approaches.

The research is published in the Journal of Clinical Endocrinology & Metabolism.

PFCs and Menopause

The 26,000 women were participants in the C8 Health Project. It collected information on more than 69,000 people from six public water districts contaminated by PFOAs from the DuPont Washington Works Plant near Parkersburg, W. Va., between August 2005 and August 2006. (C8 is another name for PFOA).

The work was funded by the settlement agreement arising from the water contamination case, Leach vs. E.I.Dupont de Nemours & Co.

Knox asked each woman about her menopausal status and then looked at blood levels of the PFCs. She found an association between high blood levels and menopause onset, she says, but not cause and effect.

For instance, women in the over 42 to 51 age group with the highest levels of PFCs were 40% more likely to have experienced menopause compared to those women in the same age group with the lowest levels of PFCs.

She also compared their blood levels of PFCs with those in the general population, using data from the NHANES survey (National Health and Nutrition Examination Survey), which reflects the U.S. population.

While PFOA levels were higher in her research participants, their PFOS levels were similar to those in the general population.

The median age of menopause is 51 (half of women go through earlier, half later), Knox says. Early menopause before the age of 40 is linked with increased risks of heart disease and with bone loss, which can raise the risk of osteoporosis.

A reverse association is possible, Knox says. Monthly menstruation eliminates some of the PFCs from the body. Early menopause may cause PFC levels in the blood to rise, she says, as monthly menstruation stops.

However, she says, even if the association is reversed, the levels are a concern, she says.

Among the study limitations is its ''snapshot in time'' factor, as it looked only at exposure at one point.

PFCs have been a concern of environmentalists for years, says Olga Naidenko, PhD, a senior scientist at the Environmental Working Group, Washington. She reviewed the study findings for WebMD.

''This is the first study to our knowledge that looks specifically at menopause timing. It really demonstrates that these kinds of chemical are very toxic."

One strength of the study is its size, says Jennifer Sass, PhD, senior scientist for the Natural Resources Defense Council, who also reviewed the findings.

"This study raises some red flags regarding a common chemical pollutant that is found in the bodies of most Americans," says Sass. "I hope that more research can be done to understand the effect better."

Industry Perspective

A spokeswoman for DuPont took exception with using the term PFCs. The term PFCs ''is not well defined and is overly broad," says Janet E. Smith of DuPont. "There are many chemicals that could potentially fall under that umbrella and they have very different properties and health profiles."

DuPont does not make PFOS or use it in its processes or product, she says. She points out that Knox found no link between PFOA and hormone levels. The company does make products with PFOA, she says.

3M decided in May 2000 to phase out production of PFOA, PFOS and PFOS-related products after research found PFOS was widely dispersed in wildlife and found in low levels in people, according to the company’s web site.

To avoid exposure, Knox suggests avoiding stain-resistant, water-resistant, and fire-retardant products. Some food containers may also have PFCs.

"Eventually we are going to have to have a policy about reducing these," she says.  However, ''we need more data before setting policy.