Modalities & Practice Management


Issues in Screening: Gathering Consensus

Stephen J. Swensen, MD

By all accounts, the route a diagnostic procedure takes to become a mass screening tool is a long and arduous journey. On its way to approval, the procedure must prove its efficacy through clinical trials, gain the support of the medical community, meet cost-effectiveness criteria, and ultimately navigate that most political of organizations: Congress. In passing the Mammography Quality Standards Act in 1992, Congress made screening mammography the first radiological screening program mandated by the federal government. It was passed into law by Congress and signed after heavy lobbying by women’s groups and others. The MQSA is administered by the Food and Drug Administration’s Center for Devices and Radiological Health. As of January 1, 1998, bone density measurement for osteoporosis screening and in selected cases the barium enema for colorectal cancer screening were added to the lineup with the passage of the Balanced Budget Act of 1997. Other screening tests covered by Medicare and approved by Congress include Pap smears, prostate specific antigen (PSA) cancer screening, and colorectal cancer screening by flexible endoscope.

“Every screening benefit we do is mandated by statute-mammography, Pap smears-nothing is added without Congress’ [approval],” explains Ellen Griffith Cohen, press officer for the Health Care Financing Administration (HCFA, now the Centers for Medicare and Medicaid Services), the agency that funds and administers Medicare. “There is no discretion in HCFA. We are not authorized under statute to pay for screening unless it is authorized by Congress.

“Congressional authorization for screening to be covered is a big push for the private sector [insurers] to consider coverage,” Cohen adds.

The Contenders

Of all the radiological screening procedures that could be considered for coverage in the years ahead, low-dose CT for lung cancer and CT virtual colonoscopy for colon cancer are particularly promising.

Unlike diagnostic imaging studies, screening studies are designed to look at asymptomatic populations. The radiation dose for screening CT is typically one-fifth of that used for diagnostic CT of the lung. Typically, a lower radiation dose is used for screening, according to the protocols of the Early Lung Cancer Action Project (ELCAP).1 Low-dose CT, however, uses two to three times as much radiation as chest radiography.

In contrast, mammography screening requires two views, with the same radiation dosage as that for diagnostic mammograms. For diagnostic procedures, however, more than two views may be taken.

Low-dose CT screening for lung cancer is being studied in a number of centers in the United States and around the world, and is offered by some hospitals and clinics. The test is not covered by Medicare or by most private health care insurance carriers in this country, although some radiologists think it could save many lives.

The seminal study of low-dose spiral CT for lung cancer screening was at the National Cancer Center Hospital in Tokyo, and was published in 1996 in Radiology.2? There are ongoing studies evaluating the procedure at three US medical centers and two in Europe, as well as at several sites in Japan, where screening is covered by government health insurance, according to the director of CT products at a company that makes scanning software.

Lung cancer is by far the leading cause of cancer deaths worldwide. In the United States, it causes more deaths than breast, prostate, cervical, and colon cancer combined. In the year 2000, it is estimated that there will be more than 1.3 million deaths worldwide. Despite new surgical techniques, chemotherapy, and radiation therapy, the survival rate for lung cancer has not improved significantly over the past 40 years. The 5-year survival rate in the United States is only 13%.

On the other hand, if discovered early enough-before it is symptomatic-lung cancer has a cure rate of nearly 70%. That is where screening programs come in.

Screening programs designed to detect lung cancer at a curable stage using chest radiography have been largely unsuccessful, but CT screening seems more promising. This newer technology finds smaller, presymptomatic lesions that can be resected, leading to greater cure rates.

CT virtual colonoscopy has not been evaluated extensively to date. Flexible sigmoidoscopy and colonoscopy are covered by Medicare and by most health insurance plans, while CT virtual colonoscopy is not. A study in the June 2001 issue of Radiology,3 however, shows that the noninvasive-type colon scan works just as well at locating precancerous polyps. Once a suspicious lesion is identified, the patient must have a standard colonoscopy to biopsy the polyps.

“Since this technique requires no anesthesia and has no risk of complications from perforation or bleeding, it may be better tolerated by patients,” states Judy Yee, MD, the study’s lead author and chief of CT and gastrointestinal radiology at the San Francisco Veterans Affairs Medical Center.

Heeding The Public Interest

But screening programs are costly. In order for HMOs to cover them, they must be cost-effective, and there must inevitably be a Medicare precedent. In some cases,

A Screening Advocate

Radiologist Irving Waldman sat down one Friday a year ago for a casual lunch in the Hollywood (Fla) Medical Center cafeteria. His companions were a thoracic surgeon and another radiologist, an Air Force buddy from the 1960s. Waldman was asked by the other radiologist if he would like to have a CT lung scan that afternoon. The radiology group had recently instituted an aggressive heart and lung screening program. Waldman’s heart scan was negative. However, Waldman, 67, had been a smoker for 26 years, but had quit 26 years earlier. He had undergone routine chest radiography in March 2000 that was negative. That afternoon, Waldman slipped onto the table for a low-dose CT scan, exactly like the ones patients pay for out of pocket at the hospital.

A few moments after his scan, the technologist told Waldman there was a small mass in his left lung. “I started to sweat a little bit,” Waldman recalls. “I took a regular chest x-ray and then called my friend from the service. I called him because I knew he is the best.”

After the friend had verified the suspicious mass and on his recommendation, Waldman called the thoracic surgeon he had just met. Four days later, Waldman had a left lower lobectomy to remove a 17-mm adenocarcinoma.

“Now it would be a shame if I was the poster boy [for screening] and something turned up in 6 months,” he notes. However, since his personal D-Day, Waldman has had two follow-up CT scans, both of which were negative, and has become a strong advocate of the screening procedure.

“It was not my idea to start screening, but our group is very aggressive,” according to Waldman, who says his group does 10-15 scans a week at a cost of $350 each, all paid for out of pocket. “My thought is there is no other way to do it currently. Chest x-ray is a waste of time. We don’t do it any more. Without question it may have saved my life.”

?-Robert Bruce

however, the public is exhibiting a marked willingness to pay out of pocket for unreimbursed screening studies.

The Ochsner Clinic and Ochsner Foundation Hospital, New Orleans, does several types of screening, according to Edward I. Bluth, MD, chairman of radiology. His special area of interest is carotid ultrasound.

“At first we were doing carotid screening for flow-limited stenosis for [predicting possible] stroke,” Bluth says. “Now we also do cardiac calcium scoring CT, and screening for lung cancer with CT. It is out of pocket; the patient pays for it on his or her own.”

Bluth and his colleagues designed their screening programs differently from some other groups. “We developed them on the same concept as screening mammography,” he notes. “We want to identify at a high sensitivity rate, not necessarily high specificity. We purposely identified all those at risk for stroke. We expect to have some false positives, then we go on to duplex ultrasound or magnetic resonance angiography.”

Bluth’s group achieved a sensitivity of 70% and a specificity of 91% in an evaluation of power Doppler screening for carotid artery stenosis.4

Although there is “no absolute proof that screening will improve outcomes, there is logic behind it,” Bluth says. “It’s not necessarily a bad personal decision by a patient to use the resources they have. People want peace of mind.

“I believe screening is a major new direction radiology is moving in,” he says. “Radiology needs to change its focus from identifying the problems of disease, to identifying the people at risk for disease. It’s a shift of the whole paradigm.”

But before it becomes a mass screening tool, and before it even gets to the federal government, a screening study goes through a rigorous process to determine its usefulness and cost-effectiveness. This usually includes randomized studies with control groups, followed by the imprimatur of major professional societies such as the American Cancer Society (ACS) and the American College of Radiology (ACR).

The most useful example is screening mammography, which has been covered by Medicare since 1992, and is covered by Medicaid in all 50 states.

“There were eight worldwide randomized controlled trials, and for many years an ACR committee followed mammographic screening,” says Marie Zinninger, associate executive director of ACR. “The first big trial was with a health insurance plan in New York City in the ’60s and ’70s. The insurer offered mammography to women, and it had a control group.”

Zinninger says that this was the first and only large screening mammography study done in the United States, with another one conducted in Canada and six in Europe.

Building Evidence

So far, neither ACR nor any other organizations have endorsed CT scanning procedures for lung or colorectal cancer, or ultrasound scanning of carotid arteries to prevent stroke. But evidence that low-dose CT can detect lung cancer significantly earlier than chest radiography is beginning to build in the medical literature.

In an unpublished study at the Mayo Clinic, Stephen J. Swensen, MD, et al studied 1,520 current or former smokers 50 years or older over 5 years, with multislice spiral CT scans at baseline and after 1 year. The researchers concluded that “CT can detect lung cancers at an earlier stage than current practice. [But] the rate of benign nodule detection is high.”

These false positives are important, Swensen says, because they mean extra cost for the health care system as well as added risk to patients.

“We discovered nearly 2,400 lung nodules in these 1,500 patients we are studying,” Swensen says. “Ninety-nine percent of these are benign-false positives. Every one of the patients needs extra tests, and some go for surgery for these benign nodules. In these instances, there are radiation risks, and the risks of surgery and anesthesia.”

The National Cancer Institute is sponsoring the Mayo Clinic trial along with others at Johns Hopkins Hospital, Baltimore, and Memorial Sloan-Kettering Cancer Center, New York.

Swensen says that decision makers have to look at the results of these studies worldwide, and when the consensus is that cost-effectiveness has been proven beyond a reasonable doubt, screening studies should be funded for high-risk groups, later for the general public.

“There’s a point at which the consensus is to stop the studies and convince third-party payors to pay for it,” he says. “I think if we can show lives are saved by this screening, it will be cost-effective. A comprehensive screening program in the United States may cost $50 billion, but that will be as cost-effective as mammography for breast cancer.

“If lung cancer mortality is actually reduced by screening with CT, I believe that the examination would subsequently be proven to be cost-effective,” Swensen says. “In general, if the cost per year of a life saved is less than $50,000, then the examination is considered cost-effective in the United States. Mammography is below that threshold.”

Is it Cost Effective?

Stephen J. Swensen, MD

Cost-effectiveness generally focuses on the longer duration of a person’s productivity and reduction of treatment costs with early detection of disease.

“All medical professionals want to do the right thing for patients and society,” he notes, “but in order to make any judgment about the ethics of it, we need to know the scientific answer. If we don’t know the truth about the scientific answer, we can’t make any judgments about ethics.

“It’s possible it will not be shown to save lives, but I think it will. It could cause some harm,” Swensen says, “if we don’t prove it? is cost-effective, since the government won’t pay and BlueCross/BlueShield (BCBS) won’t pay for it, and then it’s an examination for the rich.

“In my heart I think it can work, or I wouldn’t be spending my time on it,” Swensen says. “But it’s not at the scientific level we need for society to recommend it and for insurance companies to pay for it.”

Claudia I. Henschke, MD

In an article recently published in? Cancer,5 Cornell radiologist Claudia I. Henschke and colleagues concluded that “Annual CT screening for lung cancer provides for diagnosis at substantially earlier and thus, more curable stages and is sufficient to minimize symptom-prompted interim diagnosis of malignancies. False-positive results of the screening test were uncommon and usually manageable without biopsy.”

Henschke’s study is a follow-up on ELCAP. That preliminary study of 1,000 high-risk subjects (smokers or former smokers) showed a lot of false positives, but those were largely eliminated on the repeat screenings, Henschke says.

“There was a high percentage of false positives at baseline,” Henschke acknowledges. “But when [the patients return], I know what they had and I look for what was not there before. So now you have very few false positives. Most things that grow in the interim are cancer or pneumonia. You give antibiotics and come back in a month and see if it has either gone away or is growing.”

Henschke points out that mammography benefited from an apparent difference between men and women in their motivation to comply with screening.

R. James Brenner, MD, JD

“I never believed in gender differences in our screening until I did a survey about satisfaction. It became clear,” she says, “that women wanted results, and then they wanted action. They’re the ones who do health [care] for the family.”

The Cost Barrier

Another obstacle to funding for non-mammography screening is that CT examinations cost significantly more. The latest proposed increase in Medicare payments for mammography would bring reimbursement to $90 per examination. R. James Brenner, MD, JD, a University of California, Los Angeles radiologist, and chair of the ACR Task Force on Mammography Practice Standards, which played a decisive role in getting the recent increase in reimbursement for mammography before Congress, thinks low-dose CT screening for lung cancer has an uphill battle.

“We will screen 40 million women at $90 each,” Brenner says. “[A lung cancer] screen means 70 million to 90 million men and women, and each test is three times as expensive.”

Current Medicare reimbursement for mammography is $69. Other examples of Medicare screening benefits are flexible: sigmoidoscopy, $98; colonoscopy, $380; barium enema, $106; bone densitometry, $44; Pap smear, $28; and PSA for prostate cancer, $25. Most of these tests are covered regularly for eligible patients. Third-party payors generally follow Medicare in providing these benefits for their subscribers.

Brenner cites a recent article in Cancer6 that suggests screening for breast cancer should lower the mortality rate by 60%. “We have to decide whether that kind of outcome can be applied to lung cancer,” he says. “The issue is, can you affect mortality statistics the same as you can with breast cancer.”

Insurers Have Rigorous Criteria

Cornelia Taylor, MD

Although professional organizations such as the ACR address cost-effectiveness on a global scale, it is the third-party payors that crunch the numbers, ultimately deciding who gets which test.

Cornelia Taylor, MD, is medical director for utilization management with Regence BlueCross BlueShield of Oregon, Portland,? an HMO with some 1.2 million members. She describes the process by which BCBS decides which new technologies or procedures to cover.

“We review the medical literature based on agreed-upon guidelines,” Taylor says. “The questions that are asked when reviewing each study are as follows:

? Is this a phase I, II, or III clinical study?

? Was the assignment of patients to treatments randomized?

? What was the purpose of the study?

? Are all the clinically relevant outcomes reported?

? Are the study patients similar to the patients being considered for treatment?

? Are both statistical and clinical significance considered?

“Clinical significance here refers to the importance of a difference in clinical outcomes between treated and control patients,” she notes, “and is usually described in terms of magnitude of a result.”

When all relevant papers have been reviewed, Taylor says, BCBS’ five Technical Evaluation Center criteria are applied to the information that has been gathered:

1. The technology must have final approval from the appropriate government regulatory bodies.

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes (there is an elaborate set of rules for this criterion, Taylor says).

3. The technology must improve the net health outcome.

4. The technology must be as beneficial as any established alternatives.

5. The improvement must be attainable outside the investigational setting.

“The reviews are rigorous, no doubt,” Taylor says. “When it is clear from the evidence that a claim has been proven, we cover it. We rely on the medical literature to tell us.”

Regence BCBS of Oregon does not cover virtual colonoscopy yet, Taylor says. “At this point there are no data to suggest it is as good as currently accepted methods.” Currently covered by Regence are mammography, Pap smears, PSA, colonoscopy, flexible sigmoidoscopy, barium enema, and routine laboratory work. The radiology tests are covered based on age, the others at physician discretion.

New York’s Empire BlueCross/BlueShield is one of the funding bodies for the Henschke study at Cornell, and requires the investigators to look at long-range cost-effectiveness. So, for mass screening such as low-dose CT scanning for lung cancer, there must be both credible scientific evidence and the means to pay for it-by either Medicare, insurance carriers, or out of pocket. And how this breaks down determines just who benefits.

As Robert A. Smith, PhD, director of cancer screening for the ACS, points out, “Somebody has to pay. Payors are going to demand fairly convincing standards of evidence from a randomized control group. There is no question that a randomized clinical trial is the gold standard. These studies are enormously expensive and time-consuming, and could take up to 15 years.

“The problem is that you’ve got the availability of these tests and a significant percentage of the population that is at very high risk for lung cancer and a very high risk of dying from lung cancer. When you ask physicians and patients to postpone taking advantage of technology that’s significantly advanced over current technology, you can’t ask them to wait that long.

“When you talk about lung cancer screening, the public is not likely to have the patience to postpone decisions.”

If special interest groups pressure Congress, other screening procedures besides mammography could become mandated as a Medicare benefit. However, lung CT screens are more costly and may not have the political force behind them that mammography did.

“What pot of money is going to pay for this?” asks ACR’s Zinninger. “It’s hard to get political groups behind you to push for this kind of thing. It hasn’t happened with prostate cancer screening. Mammography may be a case study that won’t be repeated.”

Robert Bruce is a contributing writer for Decisions in Imaging Economics.

References:

  1. Henschke CI, McCauley DI, Yankelevitz DF, et al. Early Lung Cancer Action Project: overall design and findings from baseline screening. Lancet. 1999;354(9173):99-105.
  2. Kaneko M, Eguchi K, Ohmatsu H, et al. Peripheral lung cancer: screening and detection with low-dose spiral CT versus radiography. Radiology. 1996;201:798-802.
  3. Yee J, Akerkar GA, Hung RK, Steinauer-Gebauer AM, Wall SD, McQuaid KR. Colorectal neoplasia: performance characteristics of CT colonography for detection in 300 patients. Radiology. 2001;219:685-692.
  4. Bluth EI, Sunshine JH, Lyons JB, et al. Power Doppler imaging: initial evaluation as a screening examination for carotid artery stenosis. Radiology. 2000;215:791-800.
  5. Henschke CI, Naidich DP, Yankelevitz DF, et al. Early Lung Cancer Action Project: initial findings on repeat screening. Cancer. 2001;92:153-159.
  6. Tabar L, Vitak B, Tony HH, Yen MF, Duffy SW, Smith RA. Beyond randomized controlled trials: organized mammographic screening substantially reduces breast carcinoma mortality. Cancer. 2001;91:1699?1703.