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The five-year survival rate of lung cancer patients whose tumors were detected early by a CT scan is 80%, compared with 15% for patients who did not receive the CT scan. One problem with this statistic is that a CT group patient's 5 year clock starts earlier because his or her tumor is diagnosed earlier with the with the scan. This means that a CT-scan patient's tumor is at an earlier stage when the 5 year clock starts running, by comparison with a patient who did not receive the scan. So that while the tumors of a CT-scan patient and a non-CT-scan patient may start at the same time, and while the patients may lapse into cancer and die at the same time, the CT-scan patient will be said to survive more years from diagnosis. The other "numbers lie" problem is that about 4 out of 5 in the CT scan group will actually have inactive tumors that will not progress to cancer, and yet they are likely to undergo the dangers chemotherapy and/or surgery. The death rate for screened patients is actually higher than for non-screened, according to some scientists. The positive outcome for scan patients declared by the authors of the study described below are just speculation. The American Cancer Society does not endorse the scan. For a different article on this same issue click here.

New Study Sees a Gain on Lung Cancer

Gina Kolata

Researchers in New York report that millions of lives could be saved by detecting lung cancer early with annual CT scans and treating it immediately, when it can still be cured.

The stakes are high: while death rates for other cancers have fallen, lung cancer is the leading cause of cancer deaths in this country, killing more than 160,000 people a year.

For years, doctors have thought there was little they could do for lung cancer, but now with more sensitive scans, many are rethinking that view.

''You could prevent 80 percent of deaths,'' said the study's lead author, Dr. Claudia Henschke, a professor of radiology and cardiothoracic surgery at Weill Cornell Medical College.

But the report is controversial. Some medical experts and a patient advocacy group say that because this study is so much bigger than previous studies and so carefully done, it should change the testing landscape, while others say that it did not include comparison groups to demonstrate clearly that there is any benefit from annual CT exams.

The study, by researchers at NewYork-Presbyterian/Weill Cornell hospital and published today in The New England Journal of Medicine, involved more than 31,000 people in seven countries. The participants included smokers and former smokers, but also included people in Japan who had never smoked but had the scans as part of annual physical exams.

The scans found 484 lung cancers, 412 of which were at a very early stage. Then the researchers tracked those cancer patients for an average of about three years after the cancer was detected. After three years, most patients were still alive. The researchers projected that more than 80 percent of those with early-stage cancer would live at least 10 years after their cancer was diagnosed.

Supporters of the findings include Dr. James Mulshine, a professor of internal medicine at Rush University Medical Center in Chicago. The study design may not have been perfect, he said, and there is more to be learned from other studies that are now under way, but he said the data from this one was convincing.

''This is a profoundly important report,'' Dr. Mulshine said. ''It is a remarkable result.''

Members of an advocacy group for lung cancer patients, the Lung Cancer Alliance, agreed. ''This is the most important breakthrough for the lung cancer community,'' Laurie Fenton, the group's president, said in a news release.

And, says Dr. Henschke's colleague Dr. David Yankelevitz, it makes sense that early detection can save lives. Lung cancer screening is analogous to screening for breast cancer, Dr. Yankelevitz said. In both situations, he added, ''treatment is easier and the outcomes are better when the tumor is small.''

But mammograms are endorsed by many national groups, whereas lung cancer screening is not. And while praising the new study's careful accumulation of data, representatives of groups like the American Cancer Society, the American Society of Clinical Oncology, the International Association for the Study of Lung Cancer and the U.S. Preventive Services Task Force, say the study is unlikely to persuade them to recommend screening as a public policy.

One reason is that everyone in Dr. Henschke's study had CT scans. And so, researchers say, with no comparison group of people who did not have scans, they are left wondering: Does screening, in the end, save lives?

''Intuitively, it makes sense,'' said Dr. Stephen Swensen, a professor of radiology at the Mayo Clinic who conducted a study that was similar to Dr. Henschke's but smaller.

Dr. Swensen added, ''It makes sense that if you find a cancer earlier you will save lives.''

But ''the science hasn't backed that up yet,'' he said.

Cancer specialists have long known that there are cancers of all types -- and lung cancers are no exception -- that stop growing on their own, or that grow so slowly that they never cause problems. So, some ask, how many of the people said to be cured were never in danger? And how often will people have operations that can involve removing part of a lung, which is risky in itself, when their cancer was not lethal?

The problem, as with other cancer scans, is that science cannot always tell the difference between cancers that will stop and those that will not.

The researchers also ask another question: How often did the scans find cancers early but without affecting the person's life expectancy?

''Everyone knows we can pick up things better with screening,'' said Dr. Elliott Fishman, a professor of radiology and oncology at Johns Hopkins Hospital in Baltimore. ''But is picking up the same thing as curing? If I pick up a tumor that is one centimeter today and you live five years or I pick it up four years later and you live one year, it's the same thing.''

Even evaluating patients with suspicious CT results can be risky, more dangerous, say, than evaluating women with suspicious lumps on a mammogram, said Dr. David Johnson, deputy director of the cancer center at Vanderbilt University and a past president of the American Society of Clinical Oncology.

In Dr. Henschke's study, doctors investigated more than 4,000 nodules in patients, finding about 400 early-stage cancers.

''This is not sticking a needle in a breast,'' Dr. Johnson said. ''It is sticking a needle in the chest, where it can collapse a lung.'' In some cases, that is followed by surgery to further evaluate a lump. ''How many people do we subject to needless evaluations?'' Dr. Johnson asked.

It is not even clear, some researchers said, whether the patients in Dr. Henschke's study really would survive 10 years on average. The investigators used a statistical model to estimate how long patients would be expected to live after most had survived about three years.

''Ten years should be 10 years,'' Dr. Fishman said. ''It's being guesstimated out. Let's look in 10 years and see what happens.''

More definitive answers about the value of CT testing may come in a few years when another study, by the National Cancer Institute, is over. It randomly assigned its nearly 55,000 participants, smokers or former smokers, to have annual CT scans or, for comparison, chest X-rays. Based on previous studies, many researchers consider chest X-rays largely ineffective for early diagnosis of the cancer, so it can serve as a placebo control in this study.

Another institute study is assessing chest X-rays by randomly assigning participants to have an annual X-rays or to have no screening.

In the meantime, cancer specialists say doctors and their patients must decide, on an individual basis, what to do. They could wait for the clinical trials to be completed, or they could decide to have scans now, while the data may not be ideal.

And the scans can be expensive. Dr. Howard Forman, a professor of diagnostic radiology at Yale, says that Yale charges $802.39 for the scan and the doctor's interpretation.

And while many insurers do not pay for CT lung cancer screening tests, that may change, Dr. Forman said. He said he did not find this study to be convincing -- like others, he said he needed to see control group data. But Dr. Forman, who is on the Medical Policy and Technology Assessment Committee for Wellpoint, an insurance company, said it would be hard to deny paying for the test now that the data were in The New England Journal of Medicine.

''The New England Journal of Medicine is a de facto Good Housekeeping seal of approval,'' Dr. Forman said.

''It is not proof that screening saves lives,'' he said. But, he added, ''proof for a lot of medicine is not there.''

For now, said Dr. Robert Smith, director of cancer screening at the American Cancer Society, it may make sense for smokers or former smokers to have scans for early lung cancer detection.

Patients, Dr. Smith added, should discuss the test with their doctors first, going over potential benefits and potential dangers. And they should be careful to go to a center that has the expertise and experience to do the scans and any follow-up medical procedures properly.

But, he said, the new study adds to the information that CT scans might save lives.

''There is a lot of promise here,'' he said. And so, he said, ''it is not at all unreasonable for individuals at high risk of lung cancer to seek testing on their own.''

Others, like Dr. Ned Patz, a professor of radiology, pharmacology and cancer biology at Duke University Medical Center, say they suspect that patients' desire for the tests may cool once they know of the risks.

''A lot of patients ask about it,'' Dr. Patz said. ''We counsel them and tell them what the data are. Then they are not interested.''