T row specimens obtained by needle aspiration of the sternum was described by Reich in 1935.l* Subsequently, many reports of the finding of tumor cells in the bone marrow have been made. The review by Leitner' in 1949 and the recent papers by Jaimet and Amy5 and Pillers, Marks, and Mitchell9 are particularly good sources of information as to the usefulness and limitations of bone marrow aspiration as a technique for diagnosing cancer.
The history of systematic attempts to isolate or to identify malignant cells from the blood dates from the work of Pool and Dunloplo in 1934, although isolated instances of the finding of cancer cells in the blood had been reported for many years. Engel13 reported finding tumor cells in the blood of patients during operations as well as in that of patients with advanced cancer. Blood specimens taken at operations from veins directly draining the cancer frequently contained tumor cells. This publication stimulated us to make a comprehensive study of the frequency and spread of tumor cells in the blood.8114
This paper presents the results of studies designed to compare the frequency of tumor cells in sternal bone marrow aspirations with that in the blood. The term "blood" as used in this paper refers to the so-called peripheral blood obtained from an arm vein.
METHODS AND MATERIALS
This series of 600 patients cannot be considered to be unselected and thus should not be compared directly with other studies.