Thymidine phosphorylase activity in nonsmall cell lung carcinoma tissues

BACKGROUND. This is the first study on the quantitative assessment of thymi dine phosphorylase (TP) activity in patients with nonsmall lung carcinoma. TP is identical to the platelet-derived endothelial cell growth factor with its angiogenic activity. Thus, it is believed that TP activity in tumor ti ssues plays an important role in disease progression. METHODS. Using a sandwich enzyme immunoassay, the TP activity in lung carci noma tissues was measured quantitatively in 39 patients with primary lung c arcinoma who underwent pulmonary lobectomy between July 1999 and May 2000. RESULTS. The mean value of TP activity in tumor tissues was significantly h igher than the level in normal lung tissues (226 U/mg protein vs. 46 U/mg p rotein, respectively; P < 0.0001). TP activity in normal lung tissues was h igh in male patients (male vs. female, respectively, 56.1 U/mg protein vs. 29.3 U/mg protein; P = 0.001) and in heavy smokers (Brinkmann index [BI] gr eater than or equal to 600 [57.9 U/mg protein] vs. BI < 600 [31.7 U/mg prot ein]; P = 0.001). Conversely, the TP activity in tumor tissues was correlat ed with neither gender nor smoking status. Although there was no difference in the TP activity among histologic types, well-differentiated tumors exhi bited a significantly lower level of TP activity compared with the activity in both moderately and poorly differentiated tumors. However, the TP activ ity in tumor tissues was not correlated with disease progression. CONCLUSIONS. High TP activity in tumor tissues from patients with primary l ung carcinoma did not reflect the malignant potential of the disease. (C) 2 001 American Cancer Society.