Can new tumour-spotting technology save lives?
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This is a digitised version of an article from The Cayman Compass's print archive. Occasionally, the digitisation process introduces transcription errors, or other problems.
See the article in its original context from April 2002.
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By June, US governmentfunded scientists will begin enrolling 50,000 current and former smokers into a massive new research study to try to find out. Researchers hope it will eventually point toward a screening test for a top cancer killer.
"It's the most important screening trial" for any cancer in the works today, said Dr. Harmon Eyre of the American Cancer Society. Lung cancer is one of the most dismal cancers: Only 15% of those diagnosed in the United States, for example, live five years, mainly because they are diagnosed very late after symptoms begin.
But if doctors can catch a lung tumour when it is still small enough to cut out, the survival rate jumps beyond 50%. The question is how to find the tumours. Neither the US government nor cancer specialty groups recommend an annual chest X-ray, because studies during the 1970s concluded that X-ray screening did not save lives.
Such screenings must not have caught the deadliest tumours early enough to make a difference, doctors thought - or maybe they overdiagnosed less dangerous ones, putting patients through risky treatments for little reason.
But a further analysis of one of those 1970s X-ray studies, published in last week's Journal of Clinical Oncology, argues that regular X-rays could help after all.
In addition, many smokers today get a different form of cancer, called adenocarcinoma, in a different part of the lungs than they did in the 1970s, before filtered cigarettes became popular in the United States.
Many doctors wonder if modern X-rays could spot these tumours better. A National Cancer Institute project now is studying 140,000 adults, comparing annual X-rays to no screening, to see. Preliminary results are expected in 2005. But the biggest excitement in the field surrounds the new spiral CT scans. Patients lie in a rotating scanner that uses X-rays to image the chest from all angles. A computer then assembles the images into a three-dimensional model of the lungs.
Early studies suggest tumours found by spiral CT average half the size of those spotted on a regular X-ray. Cornell University's Dr. Claudia Henschke, a prominent supporter, has estimated the new method could find about 80% of tumours when they are in the earliest stage.
But Eyre said it is vital to prove the method really saves lives before testing becomes widespread.
That's because the test can mistake scar tissue from an old infection for cancer. No one knows how high this false-positive rate is, but in one Mayo study half of baseline scans detected "incidental nodules". That is important because even a biopsy can be riskier for lung cancer than other cancers - the needle can collapse a lung.
