Serum thymidine kinase in diagnosis and follow-up of the small cell carcinoma of the lung.

Serum thymidine-kinase (sTK) was assayed in 48 males affected by small cell carcinoma of the lung (SCCL) at the time of diagnosis. On the same drawing carcinoembryonic antigen (CEA) and beta 2microglobulin (beta 2 microG) were assayed in 19 of these subjects. For staging, the criterion of limited (LD) and extensive (ED) disease was used. Mean sTK and CEA values were above normal range in both the LD and ED groups, while mean beta 2 microG value remained below normal range. Thirty-two patients were subsequently submitted to therapy; sTK was assayed at the end of each treatment cycle. Mean sTK concentrations differed depending on response to therapy. From the data obtained it is concluded that sTK assay is helpful for diagnosis of SCCL; CEA to a lesser extent, above all in association with sTK, and beta microG not at all. sTK assay can also be useful for prognosis and follow-up.