Table 4.

Summary of serum sialidase and sialyltransferase changes in cancer. The columns include (1) cancer types, (2) cohort size, (3) methods used for the detection of sialylation changes, (4) major findings for each study, (5) the trend of the sialylation changes and (6) the references for each study

Malignancy	Cohort Size	Methods	Major findings	Effect in the cancer	Ref No.
Breast cancer	Cancer (n = 135)	De-sialylated fetuin as acceptor to measure the enzyme activity	Serum sialyltransferase could be a reliable marker for the monitoring of disease activity and success or failure of therapy	Serum sialyltransferase increased with higher breast cancer activity	156
Breast cancer	Cancer (n = 225); Benign breast disease (n = 100); Healthy controls (n = 100)	Sialyltransferase: de-sialylated fetuin as acceptor; total sialic acids and free sialic acid: spectrophotometric method	Serum sialic acid forms and sialyltransferase are of clinical value in monitoring clinical course and in assisting the diagnosis of breast cancer.	Increased serum sialic acid and sialyltransferase were positively associated with presence of malignant tumor and negatively with response to anticancer treatment; Malignant tissues showed elevated sialic acid and sialyltransferase	157
Oral cancer	Cancer (n = 210); Precancerous conditions (n = 100); Healthy controls (n = 100); Cancer follow-up (n = 394;after treatment)	Serum sialic acid: spectrophotometric method; Sialyltransferase: radioassay; α2–6 sialoproteins: lectin affinity chromatography.	Potential utility of serum sialic acid and sialyltransferase in prognostication and treatment monitoring of oral cancer; α2–6 sialylated proteins were associated with changes of serum sialic acid and sialyltransferase	Serum sialic acid and sialyltransferase were elevated in oral cancer	158
Prostate cancer	Cancer (n = 34); Healthy controls (n = 13);	Sialidase assays: fluorometric method	Serum sialidase (NEU3) has potential utility as novel diagnostic cancer marker	Serum sialidase activity significantly increased in prostate cancer compared with healthy	167
Breast cancer	Cancer (n = 26); Healthy controls (n = 31);	Sialidase: measured as extent of de-sialylation of fetuin or other glycoconjugates	Serum and tissue sialidase in breast cancer significantly increased compared with in the controls; There also existed significant difference between the levels of serum and tissue sialidase	Serum and tissue sialidase in breast cancer significantly increased compared with in the controls	168