- Why is health screening important?
- What Is a Screening Test?
- Cholesterol and Blood Pressure Measurements
- Cancer Screening
- Breast Cancer Screening and Mammograms
- Cervical Cancer Screening Tests
- Tests for Cancer of the Colon and Rectum
- Screening for Prostate and Testicular Cancers
- Skin Cancer Screening
- Common Health Tests Topic Guide
Why is health screening important?
Common health tests may be performed in your doctor's office, at health fairs, or even in the pharmacy. Regular health checks and screening for certain diseases and conditions have become routine for most people.
If you have any questions about exactly which tests are right for you, please discuss these concerns with your own doctor.
Screening tests for some of the less common conditions are not included here. However, it is important to be aware that just because doctors can identify someone at increased risk for a condition does not necessarily mean that it is preventable. It may simply mean that you will need to work with your doctor to closely monitor your health to ensure that the condition is detected as early as possible.
This is a brief review of some common screening health tests and it is not intended to include all of the available screening tests.
What Is a Screening Test?
Screening is a method of finding diseases in people who do not yet have any signs or symptoms of the disease being screened. The goal of screening is to help people live longer, healthier lives.
- Does screening improve health outcomes? Sometimes, a person diagnosed with the condition by screening seems to have no improvement in health when compared with a person who is only diagnosed when the disease eventually shows signs or symptoms. An example of a condition in which there is still some debate is diabetes. Although it is clear that there is probably some benefit from screening people with a strong family history of diabetes, annual screening does not necessarily seem to be useful in the general population.
- When does screening help? Screening helps when a test finds the disease or problem in a large proportion of cases. An excellent example is blood pressure. The blood pressure cuff is very accurate in diagnosing high blood pressure.
- What are the risks of screening tests? Accuracy of testing is the only risk of screening.
- However accurate a test may be, tests are never 100 % accurate, and a test may not detect a disease that is there. These called "false negatives."
- The reverse event can also occur; a test may falsely find a disease where there is none. These results are said to be "false positives." The result of a false positive may be further unnecessary testing, which may be more complex, risky, and expensive.
- Are common tests more appropriate for some people? All these factors are taken into account before a test is regularly and widely used as a routine health test. These widely used tests are discussed here. Although many screening tests may be appropriate for everyone some screening tests are more appropriate for certain groups of people.
- Examples would be Pap smears and mammography for women or regular colorectal examinations for people with a family history of colorectal cancer.
- The family history is very important to a doctor because it may point out tests that the doctor would perform in one case that may not be indicated in another person.
- What are the best or most reliable screening tests, and when should they be done? Among people in the Western world, a major cause of death is coronary artery disease. There are a number of risk factors for this condition. A risk factor is a characteristic, behavior or environmental condition that increases the chances of developing a disease when compared with a person who does not have the risk factor. Some risk factors for heart disease include a family history of heart disease, smoking, high cholesterol, diabetes, and high blood pressure.
- Some of these risk factors you cannot change. You cannot change family history, for example.
- Some risk factors are completely under your control. You can determine whether to alter that risk factor, like smoking cessation.
- Some factors could be altered through medication, dietary control, exercise, or other means. Examples are high blood pressure and high cholesterol.
Cholesterol and Blood Pressure Measurements
Blood pressure checks: High blood pressure is a risk factor for heart disease and also for a number of other diseases, such as stroke, kidney failure, and eye problems. High blood pressure may have no signs or symptoms at all, until one of these complications strikes. Measurement of blood pressure is relatively straightforward and reliable way to monitor risk and should be recorded every two years or so.
- The recommendation is that everyone over 3 years of age should have a blood pressure recorded every two years or so.
- Normal blood pressure should be no higher than 140/90, although it is clear that the lower the blood pressure (up to a point), the lower the risk.
- If a high normal blood pressure reading is detected, then blood pressure should be checked more frequently. Most doctors would recommend every year. If the blood pressure is above normal on three readings, spaced over a period of time, then therapy should begin. This should be at the discretion of the doctor, because there are cases where it is appropriate to start treatment immediately if someone has very high blood pressure readings.
Cholesterol checks: High cholesterol is a risk factor for heart disease. This seems to be particularly predictive for middle-aged men. The evidence that lowering cholesterol, especially if only slightly elevated, in women, young people, and the elderly, reduces the risk of heart disease is not as strong.
- What is meant by high cholesterol? People with cholesterol levels over 200 mg/dL are considered to have elevated cholesterol levels. An optimal level is felt to be 180 mg/dL.
- If the cholesterol level is between 200 and 240, then this is considered borderline high. Levels above 240 are high. Diet and exercise can often lower borderline high cholesterol levels, while medications are frequently recommended for high levels.
- In general, you should have your cholesterol checked every five years or more frequently if you have a previous high level.
A very important role for screening is in detecting cancer at an early stage. Although screening does not prevent cancer, it may diagnose the condition when it is in the most treatable form. It is important to note that this is not always the case though.
- A good example of this is lung cancer. Lung cancer is the leading cause of cancer-related deaths in the United States. It may seem sensible that a screening chest X-ray should be used to diagnose lung cancer. In general, though, a simple screening chest X-ray does not diagnose the condition early enough to have any significant impact on survival.
Which cancers can be detected using common health tests? Several types of cancer can be detected by testing. These include cancers of the breast, cervix, testicles, colon and rectum, and skin. There does seem to be a definite impact on survival when cancer is detected early and treated appropriately.
- The American Cancer Society offers a complete discussion of cancer screening and detection on its web site (http://www.cancer.org/).
Breast Cancer Screening and Mammograms
Although breast cancer may occur in males and females, most breast cancer screening has been directed toward females. Breast cancer is the second leading cause of cancer-related deaths in women (behind lung cancer) and the most common cancer in women. A number of screening tests have been developed to try to diagnose this disease at an early, and thus more treatable, stage. The three main tests are breast self-examination, breast examination by a health care professional, and mammography.
- Breast self-examination: This is a simple, cheap, and easy-to-perform test. The American Cancer Society recommends that women should examine their breasts once a month starting at 20 years of age. The breast self-examination should be performed in the week after the menstrual cycle, at which time the breasts are least likely to be sore or swollen. Any new lump, discharge, sore, skin changes, or other anomalies should be brought to the immediate attention of your doctor.
- Breast examination by a health care professional: It is widely agreed that all women over 40 years of age should have annual breast examinations by a health care professional. For women at increased risk, such as those with a strong family history, this should probably start earlier, at 35 years of age. Between 20 and 40 years of age, women should have breast examinations performed at least every three years.
- Mammography: This technique uses X-rays to take highly detailed pictures of the breasts. Very small lesions can be detected using this technique. Most experts recommend that women over 50 years of age have this procedure at least every year. The screening of younger women is much more controversial. Most experts agree that mammography should be performed every other year for women between 40 and 50 years of age. If there is a family history, then this should start earlier, at 35 years of age. Because of the range of opinions among experts, it is probably best for women between 35 and 50 years of age to discuss their options with their doctors, and then come to a decision together, taking into account factors such as family history and your own medical history.
Cervical Cancer Screening Tests
The incidence and death rates from cervical cancer have declined over the past 15 years or more. This is partly due to education and partly due to screening for the disease. Nevertheless, there are still about 15,000 new cases, and 4,500 deaths annually, from this condition in the United States. In developing countries, the rates are much higher. In some countries, cervical cancer is the leading cause of cancer-related death in women.
- Most cancers of the cervix are of the type known as squamous cell cancer. It is thought that these cancers can be recognized when they are in a very early (or so-called precancerous) condition. At this stage, the disease is localized to the cervix and can be treated relatively easily.
- Early treatment has an enormous positive impact on survival in this condition. This is an ideal disease for a screening test. The method used to screen for this disease is the Papanicolaou smear (or Pap smear or Pap test).
- The Pap smear is performed by viewing the cervix through a speculum and then using an instrument called an Ayer speculum to gently scrape the surface of the cervix. This leaves a residue of cells on the spatula. These cells are then spread over a microscope slide and fixed with a special chemical. The slides are then viewed under a microscope.
- All women who are sexually active, or over age 18 years, should have a regular Pap smear. How regularly they should have these is open to some debate. Most obstetrician-gynecologists (doctors who specialize in women's health) in the United States recommend a Pap test every year. An abnormal result may require more frequent screening.
Tests for Cancer of the Colon and Rectum
Colorectal cancer is the third most common cancer found in men and women and a leading cause of cancer-related deaths. Screening tests for colorectal cancer include using simple tests to detect the presence of blood in the stool (feces). These tests are called fecal occult blood tests. Doctors may also use an instrument -- the flexible sigmoidoscope -- to examine the lower parts of the bowel directly (where cancers are most commonly found).
- It is suggested that tests to look for blood in the stool should be conducted annually in everyone over 50 years of age. If there is a strong family history of colorectal cancer, then not only should testing be started much earlier, in the 30s or 40s, but testing may need to be more invasive. The doctor can take a small sample of stool and test it in the office. Sometimes it may be easier for you to provide a stool sample at home using a test kit and mailing the samples to your doctor for testing.
- For more invasive screening, a colonoscopy is performed. This test uses a long narrow flexible tube to view the entire colon. Talk with your doctor about the use of this test because the doctor will take all factors into account (for example, your family history and past medical history) to determine when you need it.
- Your doctor may require you to use a strong laxative (called a bowel cleanser) to clear your bowel of fecal contents before colonoscopy. Several medications are available for bowel cleansing, including polyethylene glycol 3350 (GoLYTELY, NuLYTELY), magnesium citrate (Citroma), and senna (X-Prep). These medications produce diarrhea, which can be uncomfortable, but unless the bowel is empty of stool, the test can be limited and may need to be repeated at a later date. Your doctor may also require a special diet, such as a clear liquid diet, starting one to two days before your scheduled colonoscopy.
Screening for Prostate and Testicular Cancers
Prostate cancer: Screening for prostate cancer is a subject of debate among doctors. It is not yet completely clear that screening is cost effective or saves significant numbers of lives. It is also not completely clear what the best screening test is. In general, the following recommendations could be made.
- Men over 50 years of age would benefit from an annual rectal examination, together, possibly with a blood test called a PSA (which stands for prostate specific antigen) The PSA test has become more controversial for screening, so discuss this with your doctor.
- Prostate cancer is a disease that affects African-American males more commonly than white males. In African-American males, screening should probably start earlier -- as young as 40 years of age.
- Men with a strong family history of the disease should also start screening at an earlier age.
Testicular cancer: Cancer of the testis represents the most common type of cancer in males between 25 and 40 years of age. The risk of the disease is increased if the man has undescended testes. Some doctors have advocated for an annual screening test or examination of the testes by a doctor. Others have suggested an educational campaign for men along the same lines as the breast self-examination guidelines for women.
- Men are encouraged to conduct monthly testicular self-examinations. Currently, no firm guidelines are in place. This is another area where discussion with your doctor would be in order, especially if you have a history of undescended testes or a family history of testicular cancer.
Skin Cancer Screening
Melanoma is a type of skin cancer that, if allowed to spread, is highly dangerous. Melanoma accounts for less than 5% of all skin cancer cases, but it causes most skin cancer deaths. Over the past several decades, the number of cases of melanoma diagnosed in the United States have been increasing. Although survival from this form of skin cancer is improving, the death rate is still increasing.
- The screening test for melanoma is a simple, relatively quick, noninvasive, and inexpensive visual examination of the skin by a trained health care professional. If there is any question about any lesion seen on this visual examination, then a skin biopsy is performed. During a biopsy or during a mole removal, a piece of tissue is removed and examined under a microscope.
- Prevention of melanoma needs to start in childhood and involves avoiding exposure to sunlight. This is achieved by wearing a hat, covering up with a long-sleeved shirt or similar clothing, and wearing sunscreen on exposed areas. The Australians developed the catchy expression "Slip Slap Slop" for slip on a shirt, slap on a hat, and slop on sunscreen.
- Although melanoma is the type of skin cancer most people are concerned about, other types of skin cancer can be equally as devastating. Again, a relatively simple visual inspection, performed on a regular basis, should be performed as part of an annual checkup. This is particularly important for people who spend a long time in the open air, or for anyone with a past history of skin cancers, or those with a strong family history.
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Fauci, Anthony S., et al. Harrison's Principles of Internal Medicine. 17th ed. United States: McGraw-Hill Professional, 2008.