Serum ribonucleases in cancer: Relation to tumor histology

Serum alkaline ribonuclease (SRNase) levels were determined in 49 normal adults and 94 patients with clinically operable malignancies. The mean SRNase levels were higher in 22 patients with adenocarcinomas (P < .003) and 28 patients with squamous carcinomas (P < .01) than in controls. These levels were also similar in patients with primary tumors only and those with metastases. The RNase levels of 21 patients with sarcomas and 23 patients with melanomas, however, did not differ from controls. The increased SRNase levels that occur early in the clinical evolution of adenocarcinomas and squamous carcinomas indicate that this change may have biological significance in the development of these malignancies. The correlation of increased SRNase levels with tumor histology may explain previous conflicting reports concerning abnormal levels of the enzyme in cancer patients.