CT scans can reduce deaths by 20 percent in older, heavy smokers by detecting tumors earlier, according to results released Thursday from an eight-year-long national study.
The study, sponsored by the National Cancer Institute and launched in 2002, aimed to see if the tests, which are more sensitive than X-rays, would affect the outcomes for those with lung cancer, the leading cause of cancer-related deaths in the country.
The disease was estimated to have killed 159,390 people in 2009, according to the institute — more people than killed by breast, prostate, colon and pancreatic cancer combined.
Many medical facilities, including Johns Hopkins Hospital and the University of Maryland Greenebaum Cancer Center, are likely to start using the scan more regularly on high-risk patients. Already, some study participants are touting it.
"The whole idea was to see if early detection increases survival, well I've survived," said a former long-time smoker, Jackie Fliegner. "Some people don't want to have a test because they don't want to know the results. They think if they have lung cancer that's it, and it's not the case."
The 65-year-old Baltimore woman was one of 1,684 Hopkins participants, and after her first scan in 2003 doctors noticed something amiss. Five years after surgery, she's cancer-free and wants to get the word out about the scans — and send a message to quit smoking, the top risk factor for the cancer.
That's also the message that officials hope to send by releasing the early data from the study, a randomized clinical trial that began in 2002 with 53,000 current and former heavy smokers who were screened at 30 sites.
Many lung cancers are not detected until they have spread, but a CT scan can not only detect a problem in high-risk patients early enough to treat it, but also improve the chances of long-term survival, said Dr. Harold Varmus, the institute director, during a news conference.
The doctors involved in the study have sent letters to the participants who had X-rays saying that they should talk to their health care provider about a CT scan.
Varmus warned that the results only apply to these older, long-time smokers. And there is much that the study did not address, such as how often a test would be needed. There also are other drawbacks. The test is not covered by most insurance or Medicare. It exposes patients to more radiation than X-rays, and it produces more false positive results that can lead to more unnecessary procedures and anxiety.
Even with the limitations, he called the results significant.
" Lung cancer is the leading cause of cancer mortality in the U.S. and throughout the world, so a validated approach that can reduce lung cancer mortality by even 20 percent has the potential to spare very significant numbers of people from the ravages of this disease," he said.
He added, "These findings should in no way distract us from continued efforts to curtail the use of tobacco, which will remain the major causative factor for lung cancer and several other diseases."
Not all lung cancer is a result of smoking, but with 90 million current and former smokers around the nation at higher risk of developing lung cancer, finding a way to diagnose and treat them has become a priority, according to the institute.
Now, most lung cancers are detected when there are symptoms, such as a persistent cough. It's spread outside the lung in up to 30 percent of cases, according to the institute. The CT scan, first used in the 1990s, is better at finding small cancers before they have spread because many more images are taken than with an X-ray, said Dr. Elliot Fishman, professor of radiology, surgery and oncology at Hopkins.
An X-ray offers one image, and what can be seen is limited, he said. A CT scan takes more than 300 "slices," each 0.75 millimeters thick, which show even small tumors. They also show nodules that developed during past infections, for example, which is why other tests become necessary, he said.
Doctors already use CT scans to find other cancers such as colon cancer, and already knew that they were more sensitive and better at helping diagnose lung cancer. But the $300 scans weren't routinely used for screening for lung cancer because there wasn't evidence that patient outcomes were better.
Fishman believes now they will be used more on long-time smokers who are at higher risk for lung cancer, even given the drawbacks. After the data is published and further reviewed, insurance also is likely to cover the practice for high-risk patients. However, he said there is still likely to be debate, as there is with most preventative tests.
"What the study ended up showing was that it does make a difference," Fishman said. "It's very positive. Twenty percent is significant. ...The bottom line is it's easy enough and cheap enough that we should just do it."
Still left to decide, he said, is how often to do CT screenings. If nothing is found in a scan, he said, he's likely to recommend no less than three years because most lung cancers grow slowly. That would put the test somewhere between annual mammograms and colonoscopies that are done every 5 years or more.
There will be more research over the next couple of years, noted Fishman and Dr. Martin Edelman, a professor of medicine at the University of Maryland School of Medicine and director of solid tumor oncology at Maryland's Greenebaum Cancer Center.
But Edelman, who helped verify the cancer study's results, said the findings were definitive and many facilities are likely to begin scanning high-risk patients for lung cancer immediately. He said his cancer center will.
He said the risk of death is reduced about the same amount as mammography reduces risk of death from breast cancer. And while it's not a cure, this scan, as well as advances in treatment, will surely give more people more time.
"There will be demand for this," he said. "It's likely to emerge as a standard of care for that population. ... It still doesn't mean it's safe to go out and smoke."