Measuring proliferation in routine fine needle aspirates. Immunocytochemical detection of bromodeoxyuridine incorporation and Ki-67 expression in breast aspirates.

Two simple quantitative means of measuring tumour proliferation which can be applied to cytological material are described. One method involves immunocytochemical staining of cytological smears prepared from breast aspirates with the monoclonal antibody Ki-67. The other method involves incubation of aspirated material with 5-Bromo-2-deoxyuridine (BrdU). Direct measurement of the S phase of the cell cycle is feasible in breast fine needle aspirates by Bromodeoxyuridine incorporation and subsequent immunocytochemical detection. The proliferation indices obtained correlate with those derived from Ki-67 staining. This technique is suitable for routine use in the assessment of tumour proliferation.