LUNG CANCER PREVENTION AND SCREENING

INTRODUCTION — Lung cancer is the leading cause of cancer death in both men and women in the United States. The number of people who die from lung cancer each year has risen over the past 25 years. The number of people who die from lung cancer is greater than the number of people who die from breast cancer, prostate cancer, and colorectal cancer combined. Several factors increase the risk of lung cancer, particularly cigarette smoking.
This topic review discusses ways to prevent lung cancer and discusses the benefits and risks of screening for lung cancer. Other topics about lung cancer are available separately.
PREVENTING LUNG CANCER — Cigarette smoking is responsible for almost 90 percent of cases of lung cancer. Exposure to certain substances, such as asbestos, has also been linked to the development of lung cancer. Exposure to second-hand smoke and other environmental factors may play a role.
The best way to avoid getting lung cancer is not to smoke. Some smokers believe that once they have smoked for a long while, it does little good to quit. However, studies have shown that smokers who quit decrease their risk of lung cancer when compared to those who continue to smoke. Smokers who quit for more than 15 years have an 80 to 90 percent reduction in their risk of lung cancer compared to people who continue to smoke.
IS SCREENING WORTHWHILE? — Screening is a way to detect a disease in its earliest stages, before a person becomes ill or dies. To be recommended, it must be clear that screening is useful in identifying patients who have the disease in the early stages, and that this discovery can reduce the number of patients who become ill and/or die.
Some screening exams have proven to make a clear difference in outcomes. Examples are the Pap smear for detection of cervical cancer in women, and colonoscopy for detection of colon or rectal cancer in people over 50 years old. These exams are now part of routine health care in the United States.
SCREENING EXAMS FOR LUNG CANCER — Research studies have been done to determine if screening for lung cancer makes sense. In these studies, smokers (who are at the highest risk) are divided into groups. Some groups have screening tests while others have no screening. The groups are then followed over many years. Data are gathered on how many patients in each group are diagnosed with lung cancer, how the cancer was treated, and how long the patients with lung cancer survived after treatment.
So far, the data from these studies have not shown that screening for lung cancer makes a difference in deaths from the disease. For this reason, expert medical advisory groups do not yet recommend lung cancer screening.
Still, the data from these studies are the subject of much debate. Part of the debate surrounds the fact that outcomes other than overall mortality, such as the stage of the disease at diagnosis and five-year survival rate, are improved in people who have screening. However, critics point out that data are difficult to interpret. The debate is continuing, and more studies are underway to better understand the role of screening studies for lung cancer.
Because of the lack of data on the efficacy of screening for lung cancer, most of the exams discussed below are not routinely recommended but are only offered to smokers as part of ongoing clinical trials. One exception may be an annual chest x-ray.
Chest x-ray — Many healthcare providers already recommend an annual chest x-ray for patients who smoke. Some experts, in analyzing data from lung cancer screening trials, have concluded that an annual chest x-ray is a worthwhile screening exam for patients with lung cancer.
Two major studies have been done to find out whether more frequent chest x-rays are helpful in lung cancer screening. So far, these studies have not shown a clear benefit in terms of deaths from lung cancer. In patients who had more frequent chest x-rays, more lung cancers were found at early stages, the cancers were more frequently removable by surgery, and the patients had longer five-year survival (from time of diagnosis) than patients with less frequent x-rays. However, overall death from lung cancer was not significantly different.
Computed tomography (CT scan) — Studies of computed tomography (CT scan) of the lung have shown that the test can help detect early stage lung cancer, but it is not yet clear whether this will affect the number of patients who die from their cancer.
Sputum tests — Some studies have looked at the efficacy of analyzing a patient's sputum for evidence of cancer cells in order to detect lung cancer. So far, no clear benefit to this approach has been found. Additional studies that use new technologies to examine the sputum are underway.
PET scan — Researchers are looking at a number of other tools in an effort to help identify patients with lung cancer. Positron Emission Tomography (or PET scanning, which uses a small amount of radioactivity to provide a detailed picture of an organ's function) has been used in combination with CT scanning.
Other studies — Direct visualization of the lungs with bronchoscopy and breath analysis for cancer markers are two tests that may be used in future studies.
CLINICAL TRIALS — Because the data on lung cancer screening are inconclusive, large-scale clinical trials of various screening modalities are underway. Smokers or former smokers may be asked to participate in these trials.
Although it makes sense to think that early detection of lung cancer is a good idea, it is important to understand that routine screening for lung cancer cannot be recommended until the research clearly shows that it makes a difference. It is likely that recommendations on lung cancer screening will evolve over the next decades as these data become available.
SUMMARY Patients who smoke are at increased risk of developing lung cancer. The best way to avoid lung cancer is not to smoke. Even long-term smokers can benefit from quitting. Researchers are looking for ways to help smokers and non-smokers who develop lung cancer to live longer. Early detection and screening is a major focus of this effort It is not clear if lung cancer screening can reduce the number of people who die from their disease. Clinical trials are underway that will help provide answers to these questions

BREAST CANCER SCREENING

INTRODUCTION — Cancer screening refers to the use of tests to detect cancer at an early stage, before it causes symptoms and hopefully at a time when it is curable. More than 200,000 women in the United States are newly diagnosed with breast cancer each year. About 40,000 women die each year of breast cancer, making it second only to lung cancer in cancer deaths among women.
The death rate from breast cancer has declined about 20 percent over the past decade . This is due, in part, to the ability of increased screening to find the disease at earlier stages when the chances of successful recovery are higher. In fact, there is more scientific evidence supporting the use of screening tests for breast cancer than for any other type of cancer.
The information presented here is for women at usual risk of breast cancer. Women with a known genetic mutation, like BRCA1 and BRCA2, or who have several close relatives with breast cancer should see "Patient information: Genetic testing for breast and ovarian cancer" for information about screening recommendations.
SCREENING METHODS — There are three main methods of screening for breast cancer: mammography, clinical breast examination, and breast self-examination.
Mammography — A mammogram is a breast x-ray. It is the best screening test for reducing the risk of dying from breast cancer. Early concerns about the radiation exposure from mammograms have lessened with the use of modern mammography equipment that exposes the breast to extremely low levels of radiation. The current level of radiation exposure is unlikely to significantly increase the risk of developing breast cancer.
The cost of mammograms is covered by most private insurances, Medicare, and Medicaid. The American Cancer Society has information about low cost mammograms that are available in most communities .
Technique — Before the mammogram, patients are asked to undress from the waist up and wear a hospital gown. Each breast is x-rayed individually. The breast is flattened between two panels, which allows the radiologist to more easily see abnormalities. This can be uncomfortable, though the discomfort lasts for only a few seconds. Mammograms are most uncomfortable when done just before or at the beginning of the menstrual period; women should try to avoid scheduling their mammogram at these times, if possible.
Findings — The mammogram is interpreted by a radiologist. Sometimes the radiologist is present at the time of the mammogram; in these cases, a patient may be asked to wait a few minutes while the radiologist determines if additional x-ray views are needed. Having additional views does not necessarily mean that a cancer is present, but instead helps the radiologist to have the most accurate image. All mammography facilities are required to send results within 30 days and the woman must be contacted within five days if the mammogram is abnormal.
Breast cancer cannot be diagnosed by mammography alone. Women usually require further testing (eg, ultrasound or biopsy) if the mammogram shows a mass, new calcium deposits, or other abnormal findings. These findings do not always mean that a cancer has been found. One study found that 11 percent of mammograms performed in the United States require additional evaluation; the area in question was not cancer in more than 90 percent of these cases .
The abnormalities that radiologists typically look for on mammograms are calcifications and masses. Macrocalcifications are large calcium deposits that most often represent degenerative changes in the breast such as might occur with aging or with previous trauma or inflammation. Macrocalcifications are common, particularly in women over the age of 50, and generally do not require a biopsy. Microcalcifications are small specks of calcium that sometimes suggest the presence of breast cancer. Depending upon the shape and pattern of microcalcifications, the radiologist may recommend a biopsy of the affected area or a repeat mammogram in three to six months.
Clinical breast examination — Clinical breast examination is peformed by a health care provider and is typically performed at the yearly physical examination. Healthcare providers usually inspect the breasts for any changes in size or shape and then palpate (feel) the breasts and the area under both arms for any change in texture or lumps.
Both clinical breast examination and mammography are important; studies show that about 50 percent of breast cancers found on screening were detected by both examination and mammography. Five to 10 percent are detected with examination and missed by mammography, and about 40 percent are detected by mammography and missed by examination.
Breast self-examination — Breast self-examination is a means of detecting changes in your own breasts. It typically is performed at the same time each month. The best time to perform breast self-examination is about one week after the menstrual period ends, when the breasts are least lumpy. In postmenopausal women who are not menstruating, the same day each month is recommended.
Most studies have not found breast self-examination to be beneficial in reducing the risk of dying from breast cancer. However, one large randomized trial found breast self-examination did result in women undergoing more breast biopsies for benign lumps . Nevertheless, some women feel that practicing breast self-examination on a regular basis improves their ability to detect subtle changes that would otherwise not have been noticed. Breast self-examination is not a substitute for mammography or breast examination by a health care professional.
The studies suggest that performing breast self-examination correctly is important. Women who want to perform self-examinations should ask their health care provider to demonstrate how to do it and how to tell the difference between normal tissue and suspicious lumps. Instructions for performing self breast examination are provided here .
Breast MRI — Magnetic resonance imaging (MRI) uses a strong magnet rather than x-rays or radiation to create a detailed image of a part of the body . Breast MRI may be recommended to aid in the diagnosis of breast cancer in selected situations [4] . MRI is not recommended to detect breast cancer in women who do not have a high risk of breast cancer because of the increased risk of a falsely positive result (when the MRI shows a suspicious mass that is not cancer). In addition, MRI is not as good as mammogram in detecting certain breast conditions, such as ductal carcinoma in situ.
DIAGNOSTIC TESTS — If an abnormality is seen on a mammogram or felt by the woman or her clinician, further testing is required to determine if cancer is present. One or more tests may be recommended, depending upon the woman's age, the location of the abnormality, and whether a lump can be felt.
Breast ultrasound — Breast ultrasound may be recommended if a mass is seen on mammography or felt during breast examination. The test uses sound waves to help determine if a breast mass is a simple cyst (fluid filled) or complex (fluid and tissue filled) or a solid tumor.
The risk of cancer is low if the mass appears to be a simple cyst based upon ultrasound; one study found no cancer in 223 simple cysts . Masses that are complex or solid have a small risk of being caused by cancer.
Ultrasound is most useful in the following situations: To evaluate a palpable mass, particularly in women under age 35 To evaluate a mass that is seen on mammography but cannot be felt
If the mass appears to be complex or solid, a breast biopsy is usually recommended.
Needle aspiration — Needle aspiration is a procedure that may be recommended to determine if a mass is cystic or solid. Needle aspiration is a reasonable option if the mass can be felt, is not too deep, or if ultrasound is not readily available or a tender cystic mass is suspected. that could be relieved by aspiration
It can be done in a healthcare provider's office, sometimes without anesthesia. The provider uses a needle and syringe to withdraw fluid from the breast mass. If the provider withdraws clear-colored fluid, the mass is unlikely to be cancer and usually resolves without further treatment. A follow up examination is recommended four to six weeks later to confirm that the mass has resolved.
However, if the fluid is bloody or if the provider is unable to withdraw fluid, the mass should be evaluated further (usually with a breast biopsy).
Breast biopsy — A breast biopsy may be recommended if an abnormal area is seen on mammography or if a mass appears to be complex (filled with fluid and tissue) or solid based upon ultrasound. The technique used to perform the biopsy depends upon the size and location of the abnormal area. Local anesthesia is usually given before the procedure to prevent pain. If the physician feels a lump, the biopsy can often be performed in the office by inserting a needle into the mass and withdrawing a sample of tissue.
If the abnormality is only found on the mammogram and the breast feels normal, the location of the biopsy must be guided with a mammogram or CT scan. The abnormality is visualized by the radiologist and its location is marked, often with a thin wire that is inserted through the skin. A surgeon uses the wire to know which area to remove.
The results of a breast biopsy are usually available within one week. If breast cancer is detected, further testing will be recommended.
RECOMMENDATIONS
Expert groups — All major North American expert groups recommend routine screening with both mammography and clinical breast examination for women ages 50 years and older. There is controversy about routine screening among women in their 40s, although over time, more and more groups are recommending screening for women in their 40s as well. The American Cancer Society, American College of Radiology, American Medical Association, United States Preventive Services Task Force, and American College of Obstetrics and Gynecology all recommend starting routine screening at age 40 years. The US Preventive Services Task Force and American Academy of Family Physicians recommends screening mammography every one to two years for women ages 40 and older . The American College of Physicians and The Canadian Task Force on the Periodic Health Examination recommend beginning routine screening at age 50 years. A 1997 National Institutes of Health Consensus Development Conference Panel Report on breast cancer screening in women ages 40 to 49 years recommended that women in this age group decide individually about breast cancer screening with their health care provider . A 2007 guideline from the American College of Physicians makes a similar recommendation .
What is "routine" screening? — Most North American expert groups suggest that women over age 50 be screened every year. Groups that recommend screening for women in their 40s have tended to shift from recommending every one to two years to recommending a mammogram every year because there is concern about more rapid tumor growth in younger women.
There are no clear data on the effectiveness of routine screening mammography in women over age 70 years. Some researchers believe that mammography is less useful in these women because they have a reduced life expectancy and tumor growth is usually slower in older women. However, most expert groups recommend that routine screening should be continued as long as a woman has a life expectancy of at least 10 years because the risk for breast cancer increases as women age. The recommended interval for women over the age of 70 is one to two years, depending upon a woman's individual risk of breast cancer.
The bottom line — All women should discuss the need for a mammogram with their clinician starting at age 40. Mammograms have the highest rate of detecting breast cancer. Virtually every well-performed study to date has found that screening mammography in women ages 50 and older reduces the risk of dying from breast cancer. A summary of trials found a 22 percent reduction in death of women in this age group who had regular mammography compared with women who did not . For women in their 40s, the protection is somewhat less, both because breast cancer is less common and because cancer is harder to find with screening (examination and imaging tests) in younger women.
There are trade-offs between the benefits and risks of mammography in detecting the following: Breast cancers (that may end a woman's life prematurely) Precancerous lesions such as ductal carcinoma in situ (DCIS) (that often do not progress) False-positive results (that cause anxiety and potentially require unnecessary testing)
All women, especially those in their 40s, should discuss their situation with a health care provider and decide together when to start screening. It is possible to compare the number of women saved from death from breast cancer with the number of false-positive mammograms or diagnosis with a precancerous lesion (DCIS).

EXERCISE

INTRODUCTION — Physical activity is any activity that involves major muscle groups, including routine daily activities such as shopping or climbing stairs. Exercise includes any activity done with a goal of improving or maintaining physical fitness.
Physical fitness can be described as the ability to carry out daily tasks with vigor and alertness, without excessive fatigue, and with ample energy to enjoy leisure time pursuits and meet unforeseen emergencies.
Many Americans have little or no physical activity in their daily lives. Approximately 24 percent of adults in the United States do not engage in any leisure time physical activity, while only about 49 percent perform the recommended amount of physical activity (at least 30 minutes of moderate physical activity five or more days per week) .
There are three main types of exercise: Aerobic exercise Resistance training Stretching exercise
This topic review discusses exercise and its benefits for adults. A separate topic discusses exercise recommendations for people with arthritis. Aerobic exercise — Aerobic exercise involves exertion such as walking, running, or swimming, which increases the flow of blood through the heart. Aerobic means "with oxygen" and refers to working at a level where the large muscles get adequate oxygen from the blood to sustain prolonged activity. Spontaneous activity (fidgeting) can burn 100 to 800 calories/day.
Resistance training — Resistance training is exercise designed to increase muscle strength, and includes lifting weights. This kind of exercise is sometimes called anaerobic, meaning "without oxygen." In contrast to aerobic exercise, the muscles do not get enough oxygen to sustain anaerobic exercise for prolonged periods of time. As an example, anaerobic exercise might involve lifting a heavy weight a number of times, after which the involved muscles are deprived of oxygen and are too fatigued to continue that level of exertion.
Stretching exercise — Stretching exercises are movements designed to improve flexibility and prevent injury. Improving flexibility allows joints to move over a wider range of motion. Good range of motion in all joints helps to maintain musculoskeletal function, balance, and agility.
BENEFITS OF EXERCISE — Apart from improving overall physical fitness, exercise has numerous health benefits: The risk of dying is decreased in those who exercise regularly. As an example, one study found that men who engaged in moderately vigorous sports had a 23 percent lower risk of death than men who were less active Exercise also helps to lower the risk of death in men with coronary artery disease . Exercise is an essential component of weight management programs. Exercise burns calories and may help to burn calories even while not exercising. Dieting can lead to loss of muscle, but exercise can help maintain muscle mass while dieting. Exercise improves blood sugar control in people with diabetes and can help prevent or delay the onset of type 2 diabetes. Aerobic exercise helps decrease blood pressure; this effect may be even greater in people with high blood pressure.Exercise often improves the blood fats (lipid profile) by decreasing triglyceride levels and raising HDL (good cholesterol) levels. (See "Patient information: High cholesterol and lipids (hyperlipidemia)"). Most people report a reduction in stress after they exercise. Research has shown that exercise is associated with reduced tension, anxiety, and depression. Weight-bearing exercise helps to prevent osteoporosis and reduces the incidence of fractures. Exercise training can improve circulation and exercise tolerance for people who have angina (chest pain from a reduced blood supply to the heart). After exercise training, a person may be able to exercise longer or at a greater intensitySome evidence suggests that exercise can provide protection against breast and prostate cancer, can delay or prevent dementia, and can decrease the risk of gallstone disease. Exercise can help with quitting smoking.
A summary of benefits is provided here .
TESTING BEFORE AN EXERCISE PROGRAM — Most people do not need any special testing before starting to exercise, but it is best to check with a healthcare provider. People with diabetes or multiple risk factors for heart disease may need an exercise test before starting an exercise program. An exercise test is performed in a doctor's office or hospital, and usually involves walking or running on a treadmill with monitoring leads on the chest.
GETTING STARTED — If you do not normally get much exercise, start by exercising for a few minutes at a low intensity (eg, walking). As physical fitness improves, you can slowly begin to exercise harder, more frequently, or for a longer time, with a goal of getting at least 30 minutes of exercise on five days each week.
Exercise does not need to be continuous to produce health benefits; it can be broken up into three or four ten-minute sessions per day. Moderate intensity exercise should be performed on most days of the week. However, exercising only one or two days per week is better than not exercising at all.
The greatest health benefits are seen in those who change from a sedentary lifestyle to being moderately active .Moderate exercise can be integrated into your daily routine with activities such as brisk walking (at three to four miles per hour), yard work, or dancing.
A simple way to start exercising is to walk. Start by walking a comfortable distance; establish a personal baseline by walking at a speed and for a length of time that is easily tolerated. Doing too much too fast may result in discomfort, disappointment, or disability from muscle pulls and strains. Try to increase your baseline distance by 10 percent each week. Measure out the distance in a neighborhood, walking trail, or shopping mall.
After reaching 45 to 60 minutes per day, you can increase the intensity of exercise by walking a greater distance in the same time. The goal is to develop a habit of regular physical activity at a level that is comfortable.
EXERCISE PROGRAM — An exercise program should include aerobic exercise, resistance training, and stretching.
Warm up — Exercise sessions should begin with a five to ten minute period of warm up. Start with some low level aerobic exercises (walking, stationary cycling, calisthenics) and then do stretches and flexibility movements. The warm-up period allows for a gradual increase in the heart rate and may reduce the risk of injuries.
Workout — It is a good idea to mix up aerobic exercise, strength training, and stretching so as to keep the workout fun and interesting.
Aerobic exercise — Walking is an excellent aerobic activity. Cycling, rowing, stair machine climbing, and other endurance-type activities are also great. Swimming and water aerobics are excellent for people with arthritis. Low impact activities are recommended because they are less likely to result in physical injury. Running on a street is a higher impact activity because of the stresses on the feet and legs as they strike the ground with each step.
The exercises should be enjoyable and simple to carry out to encourage a long-term commitment. It may be best to vary the exercises you do each week (such as swim on three of the days and walk on three of the days) to decrease repetitive strain to your muscles and other tissues.
There is no age specific heart rate recommendation; a specific heart rate is not necessary to achieve health benefits. If you are breathless, fatigued, and sweating, you have worked hard enough. During moderate intensity exercise, you should be able to carry on a conversation.
A minimum of 30 minutes of moderate intensity aerobic exercise (eg, brisk walking) is recommended on five days each week. Alternately, you can perform 20 minutes of vigorous-intensity aerobic exercise (eg, jogging) on three days each week. This recommendation is in addition to routine, light-intensity activities of daily living (eg, cooking, casual walking, shopping, etc) .
Resistance training — Resistance training can be done with weights, machines, or exercise bands. It should be performed at least twice a week with at least 48 hours of rest between sessions. Resistance training is commonly described in terms of "sets" of "repetitions." A repetition is a single completed back and forth motion of a resistance exercise, such as bending and extending the arm at the elbow while holding a weight in the hand. A set is a number of repetitions done without resting.
Most experts recommend at least one set of exercises, including 8 to 12 repetitions, for each of the major muscle groups.
Begin with minimal resistance (light weights, resistive bands, or even a can of food) to allow the muscles and other tissues to adapt. Examples of exercises for the upper body are shown in figure two ).
It is important to use proper technique. If you belong to a health club or gym might ask a trainer to observe technique. Be sure to maintain breathe normally while lifting weights. Do not hold the breath; instead, exhale with exertion. Do not perform resistance training during if you are in pain or have swelling anywhere.
Stretching — Stretching and flexibility exercises should include every major joint (hip, back, shoulder, knee, upper trunk, neck). It is best not to stretch "cold" muscles, so engage in a few minutes of low intensity aerobic exercise first. Movement into a stretch should be slow, and the stretch itself should be held for approximately 10 to 30 seconds. Do not bounce while beginning or performing a stretch.
Stretching exercises .Each exercise should be performed several times. Stretch and yoga classes are also a good way to remain flexible. The stretch should not cause pain, but only mild discomfort.
Cool down — Cool-down exercises should be done for approximately five minutes at the end of an exercise session. Similar to the warm-up period, cool-down may include low level aerobic exercise (such as slow walking), calisthenics, and stretching. This allows the body to clear acid that has built up in the muscles and allows more blood back into the circulation because less is sent to the muscles. This helps to prevent muscle cramps and sudden drops in blood pressure that can cause lightheadedness.
EVALUATING AN EXERCISE PROGRAM — Exercise should fit into the daily schedule, should be enjoyable, and should feel safe. After beginning an exercise program, most people start to notice that they feel healthier.
However, it is common for an exercise program to be disrupted by health problems, changes in job type or hours, personal relationships, and vacations. Getting back on track can be tough, but is an important step in maintaining the benefits of exercise.
If your exercise program does not fit into your daily life, try to find ways to integrate exercise so that it can remain a part of your daily routine. For example, take the stairs instead of the elevator, park in a space that is further from the door, or take a longer route to walk from one place to another.
WHEN TO SEEK HELP — In order to exercise safely, it's important to know the warning signs that could indicate a problem. If any of these problems occur, you should stop the exercise or activity and contact your healthcare provider immediately: Pain or pressure in the chest, arms, throat, jaw or back Nausea or vomiting during or after exercise Palpitations or heart flutters or a sudden burst of a very fast heart rate Inability to catch your breath Lightheadedness, dizziness or feeling faint during exercise (feeling lightheaded after exercise may mean that a longer cool-down period is needed) Feeling very weak or very tired Pains in joints, shins, heels or calf muscles (this is not an emergency, but should be evaluated if it does not resolve)
PRECAUTIONS Remember to drink fluids during and after exercise. Thirst is a good indicator that more fluids are needed. Do not exercise outdoors if the temperature is too hot or too cold. In cooler weather, it is better to wear layers of clothes while exercising outdoors. A layer of clothing can be removed if needed. Wear supportive, well-fitting running or walking shoes. Replace shoes when signs of deterioration develop (eg, cracking, separation of shoe from the sole, imprint of the foot in the insole). The amount of time exercise shoes will last depends upon a number of factors, including how often and where the shoes are worn.