Publix GreenWise Market Magazine- October 2008
Medical Tests: Is Newer Always Better?
Medical Tests: Is Newer Always Better?
The latest generation of diagnostic procedures may spot some problems sooner and more accurately. But do you really need them?
Radiologists are like big game hunters looking behind the bushes for dangerous lions in the medical jungle. That’s the image Lalit Vora, M.D., likes to conjure up as he tracks signs of disease for the City of Hope cancer center in Duarte, California, where he is a clinical professor of radiology. Vora says new screening and diagnostic tests can make the hunt for your own internal beasts easier and more precise.
But there’s a price. The tests tend to be more expensive and less widely available than their older counterparts. Sometimes the added expense and inconvenience are justified. Sometimes they’re not. Talk to your doctor about which tests are most appropriate for you. We’ll tell you what you need to know to help get the conversation rolling about screening for four conditions: breast cancer, heart disease, ovarian cancer and colon cancer.
Daniel Merenstein, M.D., director of the department of family medicine at Georgetown University Medical Center, warns against overtesting. Just because a test is available doesn’t mean you need it. What’s most important is to be actively involved in your health care. “Ask your doctors why they are doing a test,” Merenstein says. Then make sure you receive and understand the results.
Merenstein stresses that there is still a lot to be learned from the old gold standards, such as blood lipid and glucose tests or periodic Pap smears for women. Work with your doctor to get the best battery of tests for you. Newer may sometimes be better, but it pays to stick with the basics too.
Breast Cancer Screenings
WHAT’S NEW: Digital mammograms and breast MRI
BEST FOR: Younger women at high risk or with dense breast tissue; women newly diagnosed with breast cancer
Digital mammograms are fast becoming the norm at cancer centers nationally, Lalit Vora, M.D., says. Like film mammograms, the digital version uses X-rays to produce an image of the breast. The difference is that the digital images are stored on a computer. There they can be enhanced, magnified or manipulated for evaluation and comparison with previous mammograms, making small abnormalities more obvious. In addition, images can be easily retrieved for later viewing or electronic submissions to another site for remote consultation with breast specialists.
In a study published in The New England Journal of Medicine (October 2005), digital and film mammograms were about equally accurate overall. But digital mammograms were more accurate than film in certain subgroups of women, including those with dense breast tissue and women who had not yet gone through menopause.
Another technique, breast MRI (magnetic resonance imaging), uses magnets and radio waves to produce detailed images of the breast. While MRIs are more sensitive at finding breast cancer than mammograms, they also have a higher rate of false positives. To reduce unnecessary biopsies and stress, Vora says MRIs are not recommended for women at average risk. But for certain women, such as young women at high risk for breast cancer due to a family history of the disease, the American Cancer Society says getting a screening MRI along with a yearly mammogram may be valuable. For women who are newly diagnosed with breast cancer, MRIs also can detect small cancerous tumors in the opposite breast so that both breasts can be treated at the same time (The New England Journal of Medicine, March 2007).
Testing for Colon Cancer
WHAT’S NEW: Virtual colonoscopy
BEST FOR: Patients who can’t be sedated or who have difficult colons to navigate with a scope
Virtual colonoscopy (also known as CT colonography) uses an X-ray machine and computer to create 2- and 3-D images of the colon and rectum that can be manipulated for better viewing and stored for later analysis and comparison. Research has shown that it can be an effective alternative to standard colonoscopy (The New England Journal of Medicine, December 2003). As a result, joint guidelines released by the American Cancer Society and other professional groups in 2008 added virtual colonoscopy to the list of acceptable options for colon cancer screening.
But Donald David, M.D., director of the department of gastroenterology at City of Hope, worries that virtual technology might yield too many false positives. If doctors find an abnormality, they still will have to do a standard colonoscopy to biopsy it, so the patient ends up having two procedures rather than one.
Also, while the procedure is less invasive, a tube is still inserted into the rectum so air can be pumped inside the colon to expand it for better imaging. And because patients are sedated for a standard colonoscopy but not for a virtual one, some say the virtual procedure is actually more uncomfortable.
“And our patients’ biggest complaint with a colonoscopy is the bowel preparation,” David says. “That is the same with the virtual test.” On a positive note, David says virtual colonoscopy may be appropriate for patients who can’t be sedated or who have colons that are difficult to navigate with a scope.
Assessing Heart Disease Risk
WHAT’S NEW: Highly sensitive C-reactive protein blood test
BEST FOR: People at borderline risk for heart disease
A highly sensitive C-reactive protein (hs-CRP) blood test can help determine heart disease risk. The higher the CRP level—a protein whose numbers increase during inflammation—the greater the risk of heart attack. According to the American Heart Association (AHA), studies show the risk is twice as high for those in the upper third of the hs-CRP scale as those in the lower third. Sudden cardiac death and peripheral artery disease are also associated with high hs-CRP numbers.
A study published in Archives of Internal Medicine (October 2005) found that the higher the CRP is, the greater the number of other risk factors. Yet the study’s lead author notes that the test often offers little more insight than old-fashioned health sense. “If you exercise, don’t smoke, have normal levels of blood pressure, cholesterol and glucose, and are not overweight, the likelihood of having a high CRP is only one in 2,000,” says Michael Miller, M.D., associate professor at the University of Maryland Medical Center. So if you already live a heart-healthy lifestyle, a CRP test may not yield much information.
The AHA agrees that CRP testing isn’t warranted for people at low risk. Those at high risk or with heart disease don’t need the test, since they should be treated regardless of their hs-CRP level. For those at borderline risk—such as someone overweight but not obese and with somewhat elevated cholesterol—Miller says “the CRP test could be a tiebreaker for determining treatment.”
|Ovarian Cancer Screening|
WHAT’S NEW: Ovarian ultrasound in combination with CA-125 blood test
BEST FOR: Women with known strong risk factors
Scientists are testing ultrasound in combination with the CA-125 blood test to screen women at high risk for ovarian cancer. Measuring blood levels of CA-125, a marker for ovarian cancer, has been a standard means of determining the prognosis for women who’ve already been diagnosed with the disease. But as a screening tool used alone, CA-125 is unreliable, says Mark T. Wakabayashi, M.D., director of the department of gynecologic oncology at City of Hope. “Fewer than one in 30 patients with a [CA-125] abnormality has ovarian cancer. The test can show a laundry list of other things: fibroids, pregnancy, endometriosis, pelvic infections.” What’s more, some women with ovarian cancer have normal CA-125 levels.
To overcome these limitations, scientists are testing the combination of a CA-125 test and ultrasound to screen women with symptoms of or risk factors for ovarian cancer. For those at average risk, studies have found that screening did not lower the number of ovarian cancer deaths. Therefore, the American Cancer Society does not recommend the CA-125 test and ultrasound for screening of women without known strong risk factors.
On the Horizon
While not yet available for general use, the tests below show promise for identifying two hard-to-diagnose diseases.
Alzheimer’s disease. Based on recent research (Brain, March 2008), a PET scan using a tracer called C-labeled Pittsburgh Compound B (PiB) can identify signs of Alzheimer’s disease more accurately than the current standard—an MRI alone. The new test aims to pinpoint brain damage earlier, which may lead to more targeted treatment for the mildly impaired or those at risk because of family history, says the study’s lead researcher Clifford R. Jack, M.D., professor of radiology at the Mayo Clinic College of Medicine. According to Jack, the PiB test combined with an MRI could one day become standard, but research still needs to be done.
Lupus. Historically, lupus—a disorder in which the immune system mistakenly attacks the body’s own organs and tissues—has been difficult to diagnose. Now scientists at the Fred Hutchinson Cancer Research Center have developed a blood screening test that measures antibodies to SR proteins, a telltale sign of lupus. In preliminary studies the test improves the accuracy of diagnosing lupus and helps differentiate it from other autoimmune disorders such as Crohn’s disease and multiple sclerosis. Mark Roth, Ph.D., a cell biologist at Hutchinson, says the test has been approved by the U.S. Food and Drug Administration but is not yet commercially available.