The biological significance of soluble interleukin-2 receptors in solid tumors

In an attempt to further understand the biological significance of soluble IL-2 receptors (sIL-2R) in solid tumors, we have evaluated 160 cancer patients (breast: 40; lung: 66; colon: 18; stomach: 22; uterine cervix: 14) and 58 healthy subjects, as controls. Serum mean levels of sIL-2R, measured with an enzyme immunoassay, were significantly higher in cancer patients than in controls. Metastatic cancer patients showed significantly higher values than the non-metastatic ones; this difference was significant in all tumor histotypes, except small cell lung carcinoma. Moreover, in 15 patients in whom sIL-2R were evaluated either before or after radical surgery, a significant surgery-induced increase in sIL-R mean values was seen. Finally, the chemotherapy-induced rise in sIL-2R appeared to be associated with a lack of clinical response. These results seem to suggest that sIL-2R may be a marker of host biological response in patients with solid tumors, the significance of which needs further investigation.