Heat-stable alkaline phosphatase. A putative tumor marker of head and neck squamous cell carcinoma

Serum total alkaline phosphatase (AP) activity and heat-stable AP (HSAP) were investigated in patients with uncontrolled squamous cell carcinoma of the head and neck before and after treatment. No significant differences in AP activity were seen between normal subjects and cancer patients. However, the HSAP fraction of the total AP activity was significantly elevated prior to treatment and the level declined and remained low during successful treatment, while it increased with tumor progression or recurrences. Heat-stable AP was found to be a useful tumor marker of potential usefulness in the management of patients with squamous cell carcinoma of the head and neck.