To the Editor: The article by Gerber et al. (N Engl J Med 297:300, 1977) raises as many questions as it answers. Although bone scan is alleged to have a false-positive rate of only 2 to 5 per cent, in their series of base-line scans, seven positive scans were noted whereas two other patients had positive scans and negative biopsies — a base-line false-positive rate of 22 per cent. Although the phenomenon of scan conversions is assumed to represent metastatic disease, this fact is doubtful in view of the false-positive rate noted above. The authors’ advocacy of frequent follow-up bone.