Sputum cytometry could improve CT screening for lung cancer

Using sputum cytometry results to decide when to perform thoracic CT could improve screening for lung cancer, according to a recent report.

Thoracic CT is a sensitive method for detecting lung cancer, but it is associated with a high-false positive rate and it often misses early, centrally located cancers, lead author Dr. Annette McWilliams, from the British Columbia Cancer Agency in Vancouver, and colleagues note.In an effort to improve CT screening for lung cancer, Dr. McWilliams’ team decided to look at automated quantitative image cytometry (AQC) of sputum cells as a means of guiding CT use in 561 current or former smokers. All of the subjects were at least 50 years of age and had a smoking history of 30 pack/years or greater.The current findings are published in the November 15th issue of the American Journal of Respiratory and Critical Care Medicine.Of the study group, 423 subjects had sputum samples with atypia on AQC, the researchers report. Noncalcified pulmonary nodules were a very common finding on CT, identified in 46% of subjects.Fourteen cancers were detected and all but one occurred in subjects with sputum cell atypia, the authors note. Of the 13 cancers in subjects with atypia, 9 were detected by CT and 4 early cancers were detected by autofluorescence bronchoscopy. Performing AQC before CT improved the detection rate of lung cancer from 1.8% to 3.1%, the researchers note. If only CT had been performed, 29% of the cancers would have been missed. “This is the first reported study that uses the combined techniques of sputum analysis, autofluorescence bronchoscopy, and spiral CT for lung cancer screening,” the investigators point out.”This screening paradigm shift has the additional potential of reducing the number of initial CT scans by at least 25% with further savings in follow-up investigations and treatment,” the researchers add. (Source: Am J Respir Crit Care Med 2003;168:1167-1173: Reuters Health: December 17, 2003: Oncolink)