Metastatic tumor: the complementary role of the marrow aspirate and biopsy.

To determine whether bone marrow aspiration or biopsy is more sensitive in the detection of nonhematologic metastatic involvement of marrow, all 1569 consecutive paired biopsy and aspirate samples obtained between January 1975 and January 1, 1986 in an 800 bed municipal hospital were reviewed. At least eight aspirate slides and 10 biopsy cross sections were examined for each pair. In 39 samples, both biopsy and aspirate identified metastatic tumor. No biopsies contained tumor that was not also seen on the aspirate. However, five aspirate slides contained metastatic malignancies not identified on biopsy. The hematologist or oncologist viewing individual cells in a monolayer at 1000 x magnification has the advantage of identifying very small clusters of tumor cells. That accounted for three of the five positive aspirate samples in which the biopsies were negative. The other two positive aspirate slides each contained tumor on only one of eight slides. The results of our study indicate that when carefully reviewed, the aspirate is at least as sensitive as the marrow biopsy for identifying metastatic tumor. Our results indicate that marrow aspirates and biopsies are useful and complementary examinations for identifying metastatic malignancy.