Squamous cell carcinoma antigen (SCCA) is widely used as a serum marker in cancers of the uterine cervix, the head and neck, lung and esophagus. Two isoforms of SCCA, deriving from 2 highly homologous serine proteinase inhibitor genes, are co-expressed in normal and malignant squamous epithelium, but it is mainly the acidic isoform SCCA2 that is present in the circulation of cancer patients. We studied the relative levels of SCCA2 and SCCA1 mRNA in frozen sections of squamous cell carcinomas of the head and neck (SCCHN) in relation to disease recurrence, using a new reverse transcription-polymerase chain reaction-based technique for accurate quantitation of relative mRNA levels. Primary tumors from 30 SCCHN patients, recurrent tumors from 11 patients and normal epithelium from 16 controls were examined. In patients responding to initial therapy (n = 26), an elevated SCCA2/SCCA1 mRNA ratio in the primary tumor predicted recurrence independent of clinical stage (p = 0.011). The relative risk of developing a recurrence was 7.2 (CI 1.2-13.3) in patients with elevated vs. normal SCCA2/SCCA1 mRNA ratios. We demonstrate that subtle differences in expression levels of the SCCA genes are reflected in the course of the SCCHN disease and may provide a target for molecular grading of SCCHN tumors. If this finding can be confirmed in a larger study the SCCA2/SCCA1 mRNA ratio in primary tumors could be useful for individual selection of treatment strategy for patients with head and neck cancer.
Copyright 2001 Wiley-Liss, Inc.