Fast, well-tolerated tests may detect cancer before it's too late
At this year's meeting of the Radiological Society of North America, keep an eye out for several sessions that may help make radiology a household word. Thanks to recent advances in fast, multislice CT, every smoker in the nation may someday undergo a low-dose lung cancer screening exam. The same technology could also form the backbone of a well-tolerated, comprehensive colon exam aimed at curbing colon cancer deaths. Like screening mammography, the success of these tests hinges not just on detecting cancer in its early, treatable stages, but on patient compliance, ease-of-use, and cost-effectiveness. There's sure to be debates, but some radiologists are doing their homework:
The merits of annual lung cancer screening will headlined by the first baseline results of the Early Lung Cancer Action Program (ELCAP). The ongoing New York University study of 1000 smokers found that low-dose CT detected 83% of early stage cancers, which, researchers say, means annual CT screening is beneficial in high-risk patients.
Another study by the same group tackles what some see as a major drawback of early stage lung cancer screening: the detection of countless noncalcified nodules that turn out to be noncancerous, resulting in hundreds of unnecessary and costly workups. Researchers found, however, that by coupling the CT exam with risk factors such as age, gender, and number of years smoking, they were able to more accurately predict whether suspicious nodules were in fact cancerous.
And if speed and automation are the hallmarks of successful screening programs, a University of Chicago group is doing its fair share to make lung cancer screening a reality. They've developed an automated cancer detection system that uses volumetric CT image data. So far, the researchers report a preliminary sensitivity of 72% in nodule detection.
Similar inroads are being made concerning a minimally invasive colon cancer screening exam based on CT colonography. New York University researchers will present a time-efficient CT exam aimed at detecting colorectal polyps and neoplasms in asymptomatic patients. They compared a two dimensional and three-dimensional protocol, and found the former to be faster without sacrificing sensitivity. And a Harvard study touts the use of intravenous contrast. They say their protocol is especially useful in diagnosing large polyps of 10 mm in diameter, and assists in bowel wall visualization.
As for liver lesion diagnosis, a Dutch team reports that MR imaging enhanced by MnDPDP provides a correct diagnosis more often than conventional bi-phasic CT. In addition, the group's multicenter study of 151 patients found that the contrast-enhanced MR protocol beats CT in classifying the lesion. The same contrast is given top billing in a Johns Hopkins University study that compares it with biphasic CT, unenhanced MR, and sonography. The Hopkins group found that it offers equal or better sensitivity when it comes to detecting liver metastases prior to hepatic resection.
—By Dan Krotz
