Serum sialic acid is a biologic marker for malignant disease

Total Sialic Acid as a Tumor Marker for Oral Cancer

Serum sialic acid levels were measured in 80 healthy subjects, in 60 patiens with benign tumors and in 110 patients with oral cancer. It was shown that these levels were significantly elevated in oral cancer patients compared to healthy controls and patients with benign tumors (p < 0.01); they were higher in patients with stage III and stage IV disease than in those with stage I and II disease (p < 0.01). However, no difference was observed between healthy controls and stage I and II cancer patients. The results of this study suggest that the determination of sialic acid levels may be of value in the diagnosis of oral cancer, but its usefulness as an adjunct in clinical staging is limited.

Tissue and serum sialidase levels in breast cancer

Breast cancer is both one of the most common and one of the most treatable of all human malignancies. It has been suggested by various investigators that sialic acid increases in the sera of cancerous patients. In cancer patients, an increase in the levels of serum sialic acid may also be due to an increase in the activity of serum or tissue sialidase. The purpose of the present investigation was to determine whether the concentration of sialidase in serum and breast tissue could be used as a tumor marker in breast cancer. In this study; serum sialidase levels in 26 patient with breast cancer and 31 controls were found to be 77.04+/-25.07 U/l and 55.56+/-7.50 U/l, respectively. The mean tissue sialidase levels in 26 breast cancer patients and 13 controls were 39.76+/-17.03 U/g protein and 14.30+/-7.09 U/g protein, respectively. Serum and tissue sialidase levels in breast cancer were significantly higher than those found in the control group (P < 0.001). The mean serum and tissue sialidase levels in 14 Grade I-II and 12 Grade III breast cancer patients were found to be 67.73+/-11.87 U/l and 33.41+/-12.17 U/g protein and 87.89+/-31.94 U/l and 47.17+/-19.30 U/g protein, respectively. Also we found a significant difference between the levels of serum and tissue sialidase in Grade I-II and III (P < 0.05).

The prognostic importance of fibronectin and sialic acid levels in human pituitary adenomas

In this study, fibronectin and sialic acid levels were determined in human pituitary adenomas. The mean fibronectin and sialic acid levels for human pituitary adenomas were found to be 31.64 +/- 15.82 microgram/mg protein and 21.90 +/- 9.82 microgram/mg protein, respectively, versus 6.30 +/- 2.96 microgram/mg protein and 9.88 +/- 2.81 microgram/mg protein for the normal brain tissues. Fibronectin and sialic acid levels were significantly higher (P < 0.001) in human pituitary adenomas than the normal brain tissues. In human infiltrative and non-infiltrative pituitary adenomas, the mean fibronectin and sialic acid levels were found to be 40.87 +/- 15.90 microgram/mg protein, 27.59 +/- 11.10 microgram/mg protein and 22.40 +/- 9.51 microgram/mg protein, 16.21 +/- 3.20 microgram/mg protein, respectively. Fibronectin and sialic acid levels were slightly elevated (P < 0.05) in human infiltrative pituitary adenomas compared with non-infiltrative adenomas.

Tissue sialic acid and fibronectin levels in human prostatic cancer

We investigated the tissue concentration of sialic acid and fibronectin in patients with prostatic cancer. The mean sialic acid and fibronectin levels in patients with prostatic cancer were 19.02 +/- 6.30 micrograms/mg protein, respectively versus 13.01 +/- 4.53 micrograms/mg protein and 11.77 +/- 6.74 micrograms/mg protein for normal prostatic tissues. Sialic acid and fibronectin levels in cancerous patients were significantly higher than in the control group (P < 0.05).

Determination of serum total lipid and free N-acetylneuraminic acid in genitourinary malignancies by fluorimetric high performance liquid chromatography. Relevance of free N-acetylneuraminic acid as tumour marker

The reliability of total sialic acid (TSA), lipid sialic acid (LSA) and free sialic acid (FSA) as markers in genitourinary malignancies was evaluated in 20 normal subjects, 21 patients with prostatic cancer, 22 patients with urinary bladder cancer and 14 patients with renal cell carcinoma. We introduce the new concept of 'corrected' lipid sialic acid (CLSA), which expresses the actual concentration of sialic acid bound to glycolipds by subtracting the concentration of FSA determined by a novel ultrafiltration method. TSA did not show significant differences with respect to normal controls, except for renal cell carcinoma, whose mean value (879 +/- 145 micrograms/ml) showed a P value < 0.001. Instead, CLSA showed only significant differences (P = 0.001), with respect to normal controls in stage I and in all grades of renal cell carcinoma. While all data indicated significant increases (P = 0.001) in the FSA values, (means +/- S.D.) of 0.621 +/- 0.272 micrograms/ml were found in patients with prostatic cancer, 0.796 +/- 0.443 micrograms/ml in patients with urinary bladder cancer and 0.667 +/- 0.146 micrograms/ml in patients with renal cell carcinoma. Separate TSA and CLSA measurements appeared to be of limited value in the detection of genitourinary malignancies. However, results show that FSA was the most sensitive of the three markers tested for detecting malignancies.

The urinary concentration of sialic acid is increased in non-insulin-dependent diabetic patients with microangiopathy: a possible useful marker for diabetic microangiopathy

In order to investigate the relationship between urinary excretion of sialic acid and the severity of diabetic microangiopathy, urinary levels of sialic acid were determined in patients with non-insulin-dependent diabetes mellitus. The urinary molar ratio of sialic acid to creatinine in the diabetic patients was significantly higher than in the healthy controls (p < 0.01). Moreover, the urinary ratio was found to be gradually increased with the degree of diabetic microangiopathy. Urine molar ratio of sialic acid to creatinine in patients with proliferative diabetic retinopathy was significantly higher than in patients without retinopathy (p < 0.01). Urinary excretion in patients with macroproteinuria was also significantly higher than in patients without nephropathy (p < 0.01). Since urinary levels of sialic acid are proportionally increased with the severity of diabetic microangiopathy, the measurement of urinary sialic acid could become a useful biochemical means to monitor the degree of diabetic microangiopathy.

Fibronectin and sialic acid levels in human meningiomas and gliomas

In this study, fibronectin and sialic acid levels have been assayed in human meningiomas and gliomas. The mean fibronectin and sialic acid levels for human meningiomas were 22.01 +/- 9.70 micrograms/mg protein and 19.58 +/- 4.89 micrograms/mg protein, respectively, and for human gliomas were 27.30 +/- 13.70 micrograms/mg protein and 25.67 +/- 11.60 micrograms/mg protein, respectively, versus 9.23 +/- 5.40 micrograms/mg protein and 13.50 +/- 4.30 micrograms/mg protein for normal brain tissues. Fibronectin and sialic acid levels were significantly higher in human meningiomas (P < 0.01 and P < 0.05) and gliomas (P < 0.001 and P < 0.01) than control group. Also the mean fibronectin and sialic acid levels were found to be 18.27 +/- 7.08 micrograms/mg protein and 17.04 +/- 6.25 micrograms/mg protein in Grade I-II and 32.60 +/- 15.00 micrograms/mg protein and 29.50 +/- 11.60 micrograms/mg protein in Grade III-IV gliomas, respectively. Fibronectin and sialic acid levels were significantly higher in Grade III-IV gliomas than Grade I-II gliomas (P < 0.05).

The significance of serum lipid-bound sialic acid in bladder tumours

Tumour markers with high sensitivity and specificity for bladder cancer are still lacking and several markers have been investigated up to now. Serum lipid-bound sialic acid (LSA) was claimed to be a tumour marker by some investigators and this study tried to assess the value of LSA as a tumour marker in patients with bladder cancer. The results obtained from 27 patients and 30 controls showed that serum LSA levels remained within the suggested normal limits of the method used but they were significantly higher than in the controls. The value of serum LSA is questionable as an initial tumour marker for bladder cancer, but variations from the basal level may indeed be helpful in monitoring the efficacy of the therapy and in detecting relapses during follow-ups.

Serum and aqueous humor sialic acid levels in Behçet's disease

Serum and aqueous humor sialic acid (SA) levels were determined in 27 patients with Behçet's disease (Bd). Serum SA levels were elevated significantly during the active episode (mean, 113.4 +/- 4.12 mg/dl) and in the remission stages (mean, 85.4 +/- 4.79 mg/dl; P less than 0.001). A significant increase was also detected in active episodes when compared to chronic stages (P less than 0.02). Aqueous humor levels were also evaluated but could only be determined in the six eyes at the end-stage of the disease (mean, 2.65 +/- 0.60 mg/dl; P less than 0.05).

Serum sialic acid and carcinoembryonic levels in the detection and monitoring of colorectal cancer

Total sialic acid (TSA), total protein (TP), TSA normalized to total TP (TSA/TP), and carcinoembryonic antigen levels were determined in 146 consecutive colorectal patients. These results were compared with results from 73 people with nonmalignant gastrointestinal disease, and with results from 96 normal controls. All malignancies were staged according to the Astler-Coller modification of Dukes' classification for colorectal cancer. All blood samples were drawn before surgical therapy. The TSA/TP ratio for colorectal cancer was 13.4 (mg/gm) in contrast to 12.1 (mg/gm) for pathologic controls, and 9.7 (mg/gm) for normal controls. Student's t test showed a P value less than 0.001 for normal controls and a P value less than 0.001 for pathologic controls. The TSA/TP also showed statistical significance in Dukes A, B2, C, and D subgroups when compared with normal controls. There were only four patients with stage C1 carcinoma, thus statistical analysis would be questionable. In contrast, carcinoembryonic antigen levels showed no significant elevations until Dukes C2 tumors were encountered. These preliminary findings suggest that TSA/TP ratio may detect colorectal cancer patients with less tumor burden and be more beneficial as a tumor marker than CEA for monitoring patients with colorectal cancer.

Subcellular localization of sialic acid in human brain tumors

The subcellular localization of sialic acid has been investigated in various types of human brain tumors, such as astrocytoma, meningioma and primary malignant lymphoma. High levels of sialic acid were observed in the microsomal fraction of all types of tumors. However, there was no significant difference between values obtained in meningioma, primary malignant lymphoma, and normal tissue, in the fractions examining nucleus, mitochondria and supernatant.

Evaluation of N-acetylneuraminic acid, carcinoembryonic antigen, and alpha-fetoprotein as markers for advanced carcinoma

Sialic acid (N-acetylneuraminic acid, NANA), carcinoembryonic antigen (CEA), and alpha-fetoprotein (AFP) were measured in a group of patients with advanced carcinoma (primarily colorectal). The percent change of NANA was less than that with CEA, and more reliably separated patients with stable disease from those with tumor regression or progression. AFP was a good predictor of clinical course in the few patients in which it was measured.

Total and lipid-associated serum sialic acid levels in cancer patients with different primary sites and differing degrees of metastatic involvement

Serum total sialic acid (TSA) and lipid-associated sialic acid (LASA) levels have drawn considerable interest because of carbohydrate aberrations in malignant cells. The current investigation determined the TSA, LASA, total protein (TP), and TSA/TP values for 171 cancer patients with various primary sites and differing degrees of metastatic disease, 102 patients with nonmalignant diseases (pathologic controls), and 42 normal individuals. Data analysis indicated significant (p less than 0.01) increases in the mean (+/- SD) TSA and TSA/TP values in the cancer patients (78.1 +/- 19.2 mg/dl and 12.4 +/- 3.8 mg/g, respectively) and in the pathologic controls (76.0 +/- 7.5 mg/dl and 11.6 +/- 2.5 mg/g) when compared to the normal controls (67.3 +/- 7.1 mg/dl and 9.0 +/- 1.1 mg/g), and a significant decrease in the mean TP values in the cancer patients (6.4 +/- 1.1 g/dl) and pathologic controls (6.6 +/- 1.1 g/dl) when compared to normal controls (7.5 +/- 0.5 g/dl). No significant difference was observed between groups in LASA values. Further analysis of the data in patient subgroups based on the tissue involved, specific disease, or severity of the malignancy indicated that the lack of specificity of the markers was due primarily to restricted subgroups and that the sensitivity of TSA and TSA/TP increased as the malignancy became more severe. The results show that TSA/TP was the most useful of the markers tested for detecting malignancies. This marker should prove useful for monitoring malignant disease recurrence and/or progression and for evaluating the effectiveness of various therapeutic approaches.