Serum alpha-N-acetylgalactosaminidase (NaGalase) is responsible for the deglycosylation of vitamin D(3)-binding protein (Gc protein). The deglycosylated Gc protein cannot be converted into major macrophage-activating factor (MAF), leading to immunosuppression. NaGalase is universally detected in a variety of cancer patients, but not in healthy individuals (Cancer Res. 56 (1997) 2827-2831). However, the diagnostic/prognostic utility of NaGalase in squamous cell carcinoma (SCC) of the uterine cervix is not known. To address this issue, the serum NaGalase was quantitatively determined in 210 patients with different stages of SCC of the uterine cervix. NaGalase levels were increased with the progression of the cancer. After radiotherapy, the increased levels returned toward or to normal levels in early stages (FIGO stage I-IIB) but not in advanced stages (FIGO stage III-IV). The present study revealed that the amount of NaGalase in the patient's bloodstream reflects the tumor burden and aggressiveness of the disease. We conclude that NaGalase is an independent predictor of diagnosis/prognosis in SCC of the uterine cervix, and therefore suggest that quantitative NaGalase alteration may reflect important differences in the immunological functions of these neoplasms.