LOW BIOLOGICAL AGGRESSIVENESS OF SCREEN-DETECTED LUNG CANCERS MAY INDICATE OVER-DIAGNOSIS

All cases of lung cancer diagnosed in the Tampere University Hospital catchment area in 1983-1987 were identified, analyzed for DNA flow cyt ometry and followed up to 1992. The patients were classified into 3 gr oups: screen-detected, symptom-detected, and detected by chance, The b iological aggressiveness as indicated by DNA flow cytometry was not re lated to the survival of the symptom-detected patients, Also the scree n-detected patients with an aggressive tumour (aneuploid or high S-pha se fraction, SPF) had the same survival as the symptom-detected patien ts. The survival of screen-detected patients with a diploid or low SPF tumour was significantly better than that in the other groups. It is concluded that some of the previously known discrepancy of no effect o n mortality and effect on survival of lung-cancer screening may be due to over-diagnosis, i.e., detection of morphologically malignant but b iologically indolent lesions by screening. (C) 1996 Wiley-Liss, Inc.