HE INCIDENCE OF CIRCULATING CANCER
T cells varies considerably in the studies published so far. While some authors report positive findings in 5 to 7 % , 1 2 2.15921 others declare the percentage to be 10 times higher.61
The difference may be due to several factors. A number of techniques of varying effectiveness have been designed for the isolation of cancer cells from the blood. The source, number, and size of the blood samples vary from one study to another, as well as the time of sampling in relation to surgical procedure. There are also differences as to the type and site of the tumor and the extent of disease in the reported series. In addition to these factors that presumably have influenced the results, difficulties in the identification of various unusual, large benign cells have evidently caused overdiagnosis of the circulating cancer cells.lp2,151 201 23
This study covers an evaluation of the influence of various factors on the occurrence of malignant cells in blood samples from lung cancer patients. Special attention has been given to the role of operative manipulation and to the large benign cells of differential diagnostic significance.
Methods
Our series consisted of 91 patients with histologically verified lung cancer and 21 patients with noncancerous pulmonary disease, mostly tuberculosis or bronchiectasis, in addition to a few with lung abscess. In 5 cases, the tumor was too far advanced to necessitate an exploratory operation, nonresectability was evident at thoracotomy in 7 cases, and the tumor was removed at pulmonary resection in 79 cases. Among the latter, there were 61 pneumonectomies and 18 lobectomies. The