"It's wonderful technology in appropriate circumstances. It's getting better, but it's not perfect."
"”Dr. Patricia Brauening on breast MR imaging

Leading U.S. cancer killers
Lung: 162,400 (90,300 men, 72,100 women)
Colorectal: 55,100 (about 50-50 women-men)
Breast: 41,000 (almost all women)
Pancreas: 32,300 (about 50/50 men-women)
Prostate: 27,400 (men)
(2006 estimates, American Cancer Society)

Cancer of the bowel (in blue), detected by a high-speed CT scanner.

GE HEALTHCARE

You may be a current or former smoker whose family history is shadowed by the ravages of cancer. Or perhaps you don't fall into a cancer-risk profile, but you fret about it anyway"”and you're thinking about spending money on tests to ease your mind.

Research and technology keep progressing rapidly with tools for the early detection of cancer, including molecular, genetic and laboratory-based tests. The good news: catching cancer early can prevent suffering, spare lives and save our teetering healthcare system a lot of money. The bad news: many advanced tests are costly, many are not covered by insurers, and probing for cancer can be risky, to'”to your physical and emotional health. Ask any woman who agonized over a positive mammogram that turned out to be a false alarm.

Looking at early detection of cancer, we narrowed our focus here to diagnostic imaging: the world of x-rays, CT (computed axial tomography, commonly called CT or "CAT" scans), MRI (magnetic resonance imaging), ultrasound and other techniques for examining internal anatomy.

In some parts of the country, you can walk into an imaging center and have a full-body CT scan for $600, CT lung imaging for $175 or an MRI scan for as little as $400. But dependable doctors and radiologists frown on such practices. First, you get what you pay for"”and tests that might be misdiagnosed, or lead to unnecessary procedures, could cost you dearly.

Even Dr. Stephen Pomeranz, an enthusiastic advocate of diagnostic imaging, says he believes in a conservative approach when using expensive technology. He's a leading radiologist, as well as founder and CEO of ProScan Imaging LLC, which has eight imaging centers in the Tristate. Ideally, he says, a ProScan patient is referred by a doctor who has reached a professional determination that a test such as a CT or MRI scan is justified, who will communicate and coordinate with ProScan specialists if anything is found, and can help guide the patient through the next steps. "That relationship with the consulting physician is absolutely critical," he says.

It helps to know some terminology:

"¢ Screening and diagnostic exams"”a screening test is for people who do not have symptoms. A diagnostic test is for those who do. A diagnostic mammogram is more detailed than a screening mammogram.

"¢ Elective and mass screening"”when you request a test not prompted by symptoms or other factors, it's elective. Mass screening is when government health officials and the medical community endorse certain tests for groups of people on a regular basis; for instance, recommending that all men over age 50 get an annual PSA (prostate-specific antigen) test.

"¢ False positive"”when a test indicates something's wrong, such as a small tissue calcification or mass that might be cancerous, when actually it's benign.

"¢ Biopsy"”when a small sample of suspicious tissue is removed for laboratory testing to determine whether it is cancerous.

"¢ Radiation"”what you're dosed with when getting x-rays, a mammogram or CT scans. There's growing concern about the radiation risk for people who receive numerous CT scans. And radiation is one reason most medical experts say there's seldom, if ever, justification for the "whole body CT" scans that have been marketed in recent years.
If you don't have symptoms but you're concerned about cancer, the first step is a thorough "workup" by a primary care physician or internist. Pause to consider: If you're unusually anxious about cancer, how will you react if a test comes back positive? You need a reliable doctor to advise you, not a technician in a radiology center.

With all of that in mind, here's some of the latest news on early detection of the leading cancer killers, using diagnostic imaging.

LUNG CANCER
It kills far more American men and women than any other cancer, yet there is no mass screening program endorsed for lung cancer, even for the people in most danger: long-term smokers. That could change in the near future.
The biggest ongoing international study of CT screening of smokers, former smokers and people exposed to secondhand smoke recently reported that the survival rates were much higher for participants whose early stage cancers were detected by CT.

Dr. Brad Woodall, chief radiologist at Mercy Hospital Fairfield, is a passionate advocate for mass CT lung screening for those at high risk, notably current and past smokers, because lung cancer is by far a bigger killer than any other form. He notes that most breast cancers are now detected in the early Stage I or II. "Ninety percent of the lung cancers we see now are Stage III and IV," when the chances of survival are slim. "It's just horrible."

A high speed 64-slice CT scan of the lung takes about two minutes. No contrast media has to be injected, and Woodall notes that the radiation exposure is minimal.

Dr. Pomeranz believes there's definitely a future for CT lung screening under certain criteria. The increase in self-referrals to his centers has resulted in more early-stage detection.

"Five years ago I don't recall seeing a single Stage I cancer," he remarks. Now it's not uncommon to see three or four in a single day. "It's a big killer," he remarks, adding that it's hard to understand the resistance to selective screening of high-risk individuals "if done in a responsible, honest way."

BREAST CANCER
Regardless of health history, all women over age 40 should get annual mammograms. The American Cancer Society is reviewing its recommendations for women under 40 who are at higher risk of breast cancer.

Is the newer digital mammography more accurate than the standard "film screen" mammo? Initial results of a huge comparison study indicate the two x-ray technologies are about the same. Digital mammography may be better for certain groups of women: those under age 50, women who are pre-menopausal or peri-menopausal (the phase just before full menopause begins), and those who have dense breast tissue.

Dr. Patricia Brauening, director of the Women's Imaging Center at Christ Hospital, has become a convert to digital mammography. "Two years ago I would have said I'm not convinced yet," she admits. "But the technology has improved. Next year I hope we can go all-digital."

Magnetic resonance imaging (MRI) and diagnostic ultrasound also may be used for breast imaging, and "breast MR" is drawing more attention as a screening tool, especially for certain groups of high-risk women. MRI can be more accurate than mammography in detecting suspicious areas in the breast, but may not as dependable in telling which of those suspicious areas are cancerous or benign. On the other hand, MRI doesn't require the pain of breast compression, a leading reason why women skip annual mammography.

Dr. Pomeranz of ProScan was an early MRI proponent in Cincinnati in the 1990s. His local centers have conducted more than 6,000 MR breast exams, and he's excited about its potential to eventually replace mammography as the screening standard. MRI is far more accurate, he says, and can detect suspicious lesions in the most challenging patients, such as women with small breasts, those with dense tissue and those with breast implants. "If you leave here with a normal MR, most likely you don't have breast cancer," he states. "You can wait two years (for another screening) unless you have you have unusual genetics or otherwise are at higher risk."

Dr. Brauening is more reserved about MR. "It's wonderful technology in appropriate circumstances. Early on, MR produced many false positive readings. In recent years, she says, the technology has improved, as have the radiologists in interpreting the images they see. "It's getting better, but it's not perfect."

Breast imaging has benefited from computer-aided diagnostic (CAD) software. "It's kind of like a spell-checker," Dr. Brauening comments about using CAD with mammograms. "It's helpful in calling attention to lesions you could overlook. But it doesn't mark everything. I've found cancers it hasn't." She adds that CAD for MRI scans is especially beneficial.

COLORECTAL CANCER
The standard diagnostic procedures for cancer of the colon and rectum still rule: fecal occult blood tests, sigmoidoscopy and colonoscopy. But advances in "virtual colonoscopy" (or colonography) are convincing  more gastroenterologists that the imaging technique will have a role in some cases.

Virtual colonoscopy combines CT and sophisticated software to create color, 3D images of the interior surfaces of the colon, and can detect lesions as small as 6mm. It's not invasive like standard optical colonoscopy, and doesn't require sedation or anesthesia. But patients still have to go through that uncomfortable preparatory process to cleanse the bowels, and the doctor cannot remove suspicious, possibly pre-cancerous polyps, as can be done during a colonoscopy. One recent study produced good results by having both tools at hand. If the virtual colonoscopy showed lesions worth removing, the patient would undergo standard procedure during the same visit.

Two years ago, the U.S. Food and Drug Administration (FDA) first approved virtual colonoscopy software. The fact that thousands of people who avoid standard colorectal scoping might go along with a fast CT scan for an initial or followup screening means there's a future for this alternative test. "It's coming on strong," Pomeranz notes.

PROSTATE CANCER
Aside from laboratory-based tests, diagnostic ultrasound is sometimes used to check suspicious prostate glands. Some experts believe there will be more of a future role for diagnostic imaging in monitoring early-stage lesions, during that notorious "watchful waiting" period, and especially for keeping an eye on small lesions that grow quickly. For that purpose, Pomeranz believes MRI will overtake ultrasound as the prostate tool of choice.

FUTURE POSSIBILITIES
If the costs come down for advanced imaging technology, especially MRI, and manufacturers can succeed in lowering radiation exposure in high-speed CT, both may play more of a role in early detection of cancer. Much depends on the dozens of studies now under way.

Dr. Rodney Geier, an oncologist and director of radiation medicine at Christ Hospital, believes the real future of early cancer detection is in identifying genetic markers for cancer. "Over-use of imaging modalities isn't the answer at this point," he remarks.

Dr. Brauening is watching and waiting. "In the next five years we'll have more answers about what is useful, cost effective and for which populations."

RESOURCES
National Cancer Institute: www.cancer.gov
American Cancer Society: www.cancer.org
American College of Radiology: www.acr.org
Radiological Association of North America: www.rsna.org
National Foundation for Cancer Research: www.nfcr.org