Lung-cancer screening may save many lives, controversial study says

A controversial new study offers the strongest evidence yet that screening smokers for lung cancer with computerized chest scans can save lives, much as mammograms do for women with breast cancer.

Doctors have long had doubts that early detection of tumors could improve survival, and also feared that screening would lead to too many false alarms and unnecessary biopsies. Scans are not now recommended, but many smokers have been paying for them on their own for their peace of mind.

The new study strongly suggests there is a survival benefit. But it does not prove the point, because it lacked a comparison group, many scientists say.

In the study, people whose early lung tumors were detected by CT (computed tomography) scans and promptly removed had an estimated 10-year survival rate of 92 percent.

The 10-year survival rate for people diagnosed with early lung cancer is usually about 70 percent. However, 85 percent of tumors are not detected until they are more advanced and difficult to treat; for people whose cancer has spread beyond the lungs, only 5 percent survive for 10 years.

Lung cancer is the world's top cancer killer. About 174,470 Americans and 1 million people worldwide will be diagnosed with it this year. The majority will die, largely because the disease is found too late for treatment to do much good.

CT scans produce images of the lungs from many angles and can reveal pea-size growths long before they produce symptoms.

The new study "gives us greater confidence that screening may really offer advantages in saving lives from lung cancer," said Dr. Robert Smith, director of screening at the American Cancer Society, which was among more than two dozen groups that funded the study.

Even though the study lacked a comparison group, he said, "it's highly unlikely that this completely invalidates the observation of a favorable benefit from early diagnosis."

But while the research clearly shows that the interval between diagnosis and death was longer in screened patients, it does not definitively show they actually lived longer — a subtle difference with huge public health consequences.

It is not surprising that people whose lung cancers are found by a screening CT scan survive longer after diagnosis than people whose tumors are found the usual way, which is when they cause pain or breathing problems. Screened patients are diagnosed earlier and therefore will have the diagnosis for a longer time than someone whose tumor is found later, even if the two people die at exactly the same time.

Gary Kelloff, an oncologist at the National Cancer Institute, said of the new study: "I think it provides valuable information on many things. What it doesn't do is prove that you can reduce the number of people who will die from lung cancer."

But Laurie Fenton, president of the Lung Cancer Alliance, an advocacy group, said: "We think this is a breakthrough for lung cancer. I think we have enough data to move forward and apply this to a high-risk population."

In the study, reported in today's New England Journal of Medicine, dozens of researchers around the world screened 31,567 people at high risk of lung cancer because they were current or former smokers or had been exposed to a lot of secondhand smoke.

Swedish Medical Center in Seattle was one of the 38 medical institutions participating in the study. About 600 people were screened at the hospital.

Participants were initially screened between 1993 and 2005, and the majority came back for repeated screenings about a year later. Thirteen percent of those who were initially screened, and 5 percent who had repeated screenings had suspicious spots that required further testing. Biopsies were performed on 535 patients; 484 were diagnosed with lung cancer, including 412 in the early stage. Most had surgery or chemotherapy. Eight were untreated; the reasons were not specified in the paper.

Researchers then calculated survival probability using a common statistical tool. The estimated 10-year survival rate, regardless of when the cancer was diagnosed or the type of treatment, was 80 percent.

That increased to 88 percent if the cancer was detected in an early stage, and to 92 percent if such patients had surgery within a month of diagnosis. The eight untreated patients all died within five years of diagnosis.

"When you find [the cancer] when it's small, you can essentially cure most of them," said Dr. Claudia Henschke of New York-Presbyterian Hospital/Weill Cornell Medical Center, the study's lead author.

The scans cost between $200 and $300, roughly double the price of a mammogram. Insurers are not covering lung scans because the government does not recommend them.

National cancer organizations also currently don't recommend screening for lung cancer, and this study seems unlikely to change that stance.

"Health policy isn't made on the basis of one study," said Smith of the American Cancer Society.

The study "raises great hope for CT screening," but it doesn't prove a benefit, said Dr. Denise Aberle of the University of California, Los Angeles, who is helping conduct a government-funded study that should give more definitive answers. It is screening 53,000 current and former smokers with CT scans or regular chest X-rays to see whether either can cut lung-cancer deaths. The Mayo Clinic also is leading a screening study, and others are under way in Europe.

Until there is proof, patients considering screening should ask their doctors about the pros and cons, said Dr. Joan Schiller, a cancer specialist at the University of Texas Southwestern Medical School.

"They need to know that the chances are good that something abnormal will be found," which could lead to false alarms, she said.

Because many abnormal scans will lead to biopsies that involve sticking a needle into the lungs, "you need rather strong evidence that [screening] does what you think it does, namely reduces mortality," said Constantine Gatsonis, a biostatistician at Brown University, in Rhode Island.

Material from Seattle Times staff reporter Warren King, the Chicago Tribune and Los Angeles Times is included in this report.