Serum lysozyme levels in patients with solid tumors

Serum lysozyme has been demonstrated to be an indicator for macrophage activity in the tumor-bearing host. Therefore, we investigated lysozyme levels in the sera of 336 untreated tumor patients (121 malignant melanoma, 61 lung cancers, 70 cervical cancers, 49 breast cancers and 35 benign breast tumors, and 36 healthy controls). Patients with malignant melanoma and lung cancer had significantly higher lysozyme levels than the healthy controls. Within the clinical stages in melanoma, there was a decrease of lysozyme in stages II and III in comparison to stage I, but still above that of the control values. Patients with benign breast tumors had normal levels, whereas in breast cancer patients of stages I and II there was a significant reduction in the lysozyme levels. In stages III and IV no differences to the control group could be detected. In patients with cervical cancer (FIGO II and III) serum lysozyme levels were found to be within the normal range. From this study it can not be concluded that serum lysozyme reflects the immunological reactivity of the tumor bearer. Nevertheless, the reduced levels in stages I and II of breast cancer might point to an immunological defect.