March 28, 2008
prevention.com

When the Best Tests Fail

Health screenings can save your life--if they work right. What you do can make all the difference

When it comes to protecting your health, few advances pack the oomph of a good screening test. Take a look at the taming of cervical cancer: Fifty years ago, the disease claimed the lives of more women each year than any other cancer. Then doctors started using the Pap test, which can catch cervical cancer before it starts. And now cervical cancer has dropped to number 15 on the list of cancer killers of American women.

Yet even a great screening test can have crucial weaknesses. The Pap isn't perfect. And a recent study on the colonoscopy found that some doctors do the exam so quickly that their patients don't get the procedure's full lifesaving benefit.

Fortunately, you don't have to lose out--if you know what to do and say. Make sure you get the best from four common screenings.

Prevent Colon Cancer

Katie Couric's colonoscopy on Today in 2000 prompted 20% more people than expected to get the exam in the following 9 months. After that, the increase tapered off but didn't disappear. That makes doctors happy: In part because of increased screening, deaths from colon cancer dropped from more than 57,000 in 2000 to 53,580 in 2004, according to the CDC.

During a colonoscopy, a doctor inserts a flexible, lighted tube into the rectum and guides it into the colon to look for and remove growths called polyps, which are the source of most colon cancers.

But the test may not always catch a patient's cancer. One reason: Last December, a New England Journal of Medicine study of one gastroenterology practice found that doctors who rush find fewer polyps.

"If you spend more time looking for weeds in a garden, you're going to find more weeds," says Robert L. Barclay, MD, the lead author of the research, which examined his own office in Rockford, IL. "The physician in our practice who averaged the longest inspection time [nearly 17 minutes] found 10 times as many polyps as the physician with the shortest average time [about 3 minutes]." Because colonoscopies are recommended just once a decade, a slower test could make a critical difference.

Tune Up Your Test

Ask how many colonoscopies your physician typically does before lunch. Ten is a reasonable number.

Encourage your doctor to watch the clock: In the Rockford practice, setting a minimum of 8 minutes for withdrawing the scope increased the overall detection rate by 40%.

Make the prep more palatable with a pill. Before the exam, patients generally drink large quantities of a nasty tasting, laxative-like substance to clean out the colon; simply consuming the liquid is such an unpleasant experience that it can keep people from getting screened. But research shows that a new tablet called OsmoPrep is just as effective--and much easier for the patient. (Some conditions, like kidney disease or cardiovascular problems, rule out OsmoPrep; check with your doctor.)

Ward Off Cervical Cancer

Between 1955 and 1992, the death rate from cervical cancer dropped by 74%, thanks to the Pap test, in which doctors take a sample of cells from the cervical area and send it to a lab for evaluation. But for every five women who have cancerous or precancerous cervical cells, at least one will have a test mistakenly reported as normal, according to the National Institutes of Health.

Because cervical cancer develops slowly, the woman's next test should catch the problem in time. Still, getting one of these "false negatives" sometimes means a dangerous delay in diagnosis and treatment.

Tune Up Your Test

Ask about the tools your doctor uses. Studies show that doctors get a better sampling of cells when they use a "spatula" (for the opening to the cervix) in combination with a cytobrush, which looks like a mascara wand (for the opening of the uterus). An instrument called a "broom"--like a miniature janitor's broom--is less effective, says Lucille Marchand, MD, a professor in the Department of Family Medicine at the University of Wisconsin School of Medicine and Public Health. If your doc uses the broom, it's a sign that he or she isn't up-to-date, Marchand says--good reason to consider a switch.

Get a "liquid-based" test such as Thin Prep or Sure Prep. Cells are less apt to clump together or be obscured by mucus with these methods, so it's easier to detect cancer if it's present, according to Kenneth L. Noller, MD, president-elect of the American College of Obstetricians and Gynecologists. About 80% of gynecologists use this more accurate technology.

Consider getting an HPV test to screen for human papilloma virus, the culprit behind most cases of cervical cancer. The HPV test, used with the Pap to screen women over age 30, assesses whether you're infected with any of the 13 HPV types that are linked to the cancer; a positive result on both tests may lead your doctor to perform a colposcopy, in which your cervix is inspected through a kind of magnifying glass.

The HPV test is also approved for younger women if a Pap test indicates a possible problem. (Most women are able to fight off the virus; only those who are unable to get rid of it go on to develop pre-cancer of the cervix.) For women over age 30, says Noller, "having this test along with a Pap smear once every 3 years is more accurate in picking up cancer than getting a Pap every year."

Watch the calendar to keep your smear clear. It's best to schedule your test when you're not menstruating--day 10 to 14 of your cycle (day 1 is the first day of your period). Avoid tampons, douches, contraceptive jellies, yeast creams, and sexual intercourse for 72 hours prior to your exam. Go ahead with the exam if that's the only time you can do it--but "these make it more likely there will be a suspicious finding that's not actually cancer," says Noller, which can lead to unnecessary follow-up tests.

Detect Breast Cancer

The most basic breast cancer screening test, the mammogram, stirred a lot of controversy a few years ago when Danish researchers argued that there was no good evidence behind its widespread use. After analyzing the studies, the American Cancer Society and the National Cancer Institute came out soundly in favor of the test for women starting at age 40.

For women 50 and older, the US Preventive Services Task Force says an annual mammogram cuts the risk of dying of breast cancer by 16%% or more; in one recent large study, the risk was cut by up to 45%. Still, the test has flaws. It can indicate an abnormality when one isn't really there, leading to lots of worry and more tests--including biopsy. Out of every three women screened over a period of 10 years, one gets a false alarm. Scarier, studies have shown that in about 20% of cases where cancer is present, a mammogram doesn't detect it.

Tune Up Your Test

Ask for a double-check of your x-ray. When you call for an appointment, ask the imaging facility about its reading practices: Ideally, your films will be read by two radiologists or scanned by computer-assisted detection (CAD) technologies. "These provide a second set of eyes, and studies suggest they can make a difference," says Daniel C. Sullivan, MD, director of the Cancer Imaging Program of the National Cancer Institute. "CAD improves diagnosis as much as 20% for some radiologists."

Take your x-rays with you if you change imaging facilities. Screening is more powerful if your doctor can compare new images against old ones to track the changes over time.

Consider going high tech if you're at increased risk. Women who have a mutation in the genes known as BRCA 1 or 2 should have an MRI each year along with their mammogram, according to Ellen Warner, MD, a medical oncologist at Toronto Sunnybrook Regional Cancer Centre in Ontario. In her study of 236 high-risk women, MRI found 77% of cancers, compared with 36% detected by mammography. Despite these impressive stats, women at average risk are not encouraged to get an MRI because of its high false-positive rate--it often signals cancer when none is present.

Schedule your mammogram during the first 2 weeks of your cycle if you're premenopausal to avoid the hormonal shifts that can make breasts more sensitive, says Barbara Jaeger, MD, director of women's imaging at Mercy Medical Center in Baltimore. Also, lay off caffeine for a week before the test--it increases tenderness, too.

Cushion your breasts to ease the pressure. In studies of more than 1,300 women, a cushion called the MammoPad reduced discomfort by nearly half for 70% of women, Jaeger says. In her research, that relief let technologists compress women's breasts more, producing better pictures. The MammoPad is used in about 1,500 imaging centers across the country.

Skip deodorant--and powders, creams, and perfume--on the day of the mammogram. These can interfere with the reading.

Find Skin Cancer

Melanoma, the most dangerous form of skin cancer, has a grim distinction: Among cancers that can be screened for, it's the only one for which both the number of new cases and the death rate are on the rise. Yet the US Preventive Services Task Force, which sets the most widely accepted list of recommended screening tests, doesn't include a skin check in their recommendations.

In January, a study found that even a single melanoma screening at age 50 would be a cost-effective way to pick up the disease in the early stages. The American Cancer Society suggests getting a once-over at every checkup. "We know survival is much better when diagnosis is early," says lead study author Elena Losina, PhD, an associate professor of biostatistics at Boston University School of Public Health.

Tune Up Your Test

Put all your doctors to work, because melanoma can occur in surprising spots that are difficult to examine yourself, like the eyes, gums, and genitals. A full-body check is your best protection; also ask your dentist, eye doctor, and gynecologist to look for pigmented lesions or other suspicious changes during routine exams.

Know the ABCDs of healthy skin. Monitor moles and other growths for asymmetry, border (ragged or irregular), color (uneven shades of brown, black, tan, even blue), and diameter (larger than a pencil's eraser). But tell your doc about any change--even in a smaller mole, Losina says: "Self-screening is crucial--especially at midlife."

See a specialist if you spot something suspicious. A 2006 study from Emory University showed that dermatologists are best at detecting the cancer. Skin doctors picked up 89% of melanomas, compared with 80%% identified by primary care docs.

Breakthrough ways to screen for the silent cancers

Some diseases are so difficult to detect they're almost always deadly by the time they're found. But these new approaches might make a lifesaving difference in some of the toughest cases.

Ovarian Cancer

Women are scared of ovarian cancer for good reason: In 80% of cases, it isn't discovered until it's too late to cure. Yet tests--an ultrasound of the ovaries and a blood test that measures levels of CA-125, a protein known to rise when there's cancer--are useless for women at average risk.

The reason: If those exams suggest disease, the typical next step, at least for women past menopause, is to remove the ovary for biopsy. But the tests are so inexact that doctors would have to remove 100 women's ovaries to find a single case of cancer, says Edward E. Partridge, MD, interim director of the UAB Cancer Center at the University of Alabama at Birmingham.

Partridge's research holds out hope that testing will soon become less invasive and more accurate. In his study of 34,000 postmenopausal, asymptomatic women, doctors didn't do a biopsy unless a woman had a worrisome change on an ultrasound and her CA-125 level was over 65 U/ml--nearly double what's generally considered elevated. The result: Researchers found cancer in 1 out of every 5 women biopsied.

In 2 years, the study will show whether those women survive longer than others who weren't screened. If they do, ovarian cancer will still be silent--but the tests may blare a priceless warning.

Lung Cancer

Like ovarian cancer, lung cancer in its early stages often causes no symptoms--or vague ones that are easily missed. So 4 out of 5 lung cancers are found in a late stage, often after they have spread to other places in the body, when there's little chance of a cure. Yet a recent large study showed that a CT scan of the lungs is remarkably successful at finding these cancers early.

When researchers at Cornell University scanned the lungs of 31,000 ex-smokers, they found cancer in 484 patients--85% of them at an early stage. Treatment at that point affords a 92% chance of surviving 10 years, says lead researcher Claudia Henschke, MD, a professor of radiology at Weill Medical College at Cornell University.

Why shouldn't everyone get a scan? First, it's not yet clear that the test will actually lengthen anyone's life. Further studies will show whether patients whose lung cancer is detected early live longer--or simply go through treatment longer but die at the same time as patients whose cancer was not detected this way. Also, there's concern about harm if doctors are too quick to biopsy patients with suspicious findings; a biopsy needle can collapse a lung. Still, the scan is worth considering if you're over 50 and have smoked at least half a pack a day for 20 years or more at any time in the past, according to Henschke.