Lung cancer: For doctor pushing CT scans, a vindication
3-D scans reduced deaths from lung cancer by 20 percent over just five years.
Thu, Nov 04, 2010 at 09:16 PM
SCANNING TO SAVE: People who got the CT scans were not only 20 percent less likely to die of lung cancer, but they were 7 percent less likely to die of anything than people who got ordinary chest X-rays. (Photo: ZUMA Press)
Dr. Claudia Henschke was delighted with the news — a trial of 53,000 people had shown that screening smokers and ex-smokers for lung cancer can save lives, something she has been trying to prove for 10 years.
The trial, sponsored by the National Cancer Institute and conducted with the utmost care, showed that the three-dimensional X-rays called spiral CT scans reduced deaths from lung cancer by 20 percent over just five years.
It was no surprise to Henschke, who has shown even more profound results in a series of studies. And she says she is not bitter that her data, and her advocacy for screening, have been rejected repeatedly by many other cancer experts.
"I'm thrilled, because it makes such a difference for people's lives," Henschke, formerly of New York Presbyterian Hospital-Weill Cornell Medical Center and now at the Mount Sinai School of Medicine, said in a telephone interview.
She does feel some exasperation, although she understands the logic of the scientific process, in which one researcher makes a discovery, publicizes it, and other researchers try to replicate the findings — or poke holes in them.
In 1999, Henschke and other researchers found that spiral CT scanning could detect 85 percent of small lung tumors while they could still be surgically removed. The study started a debate about whether such scans were worthwhile for all smokers.
"This has now taken 10 years," she said. "If you think about it, in the United States we have 160,000 deaths each year from lung cancer. That's 1.6 million."
In 2006, her team published similar findings in the New England Journal of Medicine, sparking intense debate. Although her study involved more than 31,000 people at high risk of lung cancer, many cancer experts rejected the conclusion that screening made sense.
They pointed to the high risk of so-called false positives, meaning a suspicious-looking image would turn out to not be cancer. They also noted that some lung tumors might be removed — a major surgical operation — that would never have killed the patient.
Tobacco company funding
And then it emerged that a tobacco company had helped pay for the research and some critics suggested that cigarette makers just wanted to give smokers an excuse to keep on smoking.
Henschke rejects this idea.
"It was felt that the tobacco companies should pay for the damage that they had caused," she said.
The study had been done to support the argument that tobacco companies should foot the bill for screening smokers and former smokers, Henschke said.
Henschke also points out that most people now being diagnosed with lung cancer had either quit smoking, or had never smoked — something that Dr. Bruce Johnson of the American Society of Clinical Oncology backs up.
"You get more bang for your buck if you quit smoking," he said. "That said, if you have already quit, you can't quit again."
For her part, Henschke had her doubts about the trial released on Thursday.
"We were always concerned that it might not show (a benefit) because there was a chest X-ray arm and a CT arm and only three years of screening were provided," she said.
"Each year it should show a bigger reduction for mortality. Had they screened for 10 years, they would have come up with what we found — a 70 percent reduction in lung cancer deaths. If they screen long enough and follow everyone long enough, they should get to that point, too."
Thursday's trial showed that people who got the CT scans were not only 20 percent less likely to die of lung cancer, but they were 7 percent less likely to die of anything than people who got ordinary chest X-rays, which are virtually useless for detecting small lung tumors.
National Cancer Institute director Dr. Harold Varmus said it is not immediately clear why this is, but Henschke thinks she knows why.
"The low dose spiral CT is not just screening for lung cancer. It is screening for COPD (chronic obstructive pulmonary disease, which includes emphysema) as well as cardiovascular disease," she said.
Her team has a study in the journal Radiology that shows the spiral CT can show hardened places in major blood vessels called coronary calcifications — which in turn can tell who is at risk of heart attacks, strokes or artery disease.
(Editing by Eric Walsh)
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