Expression of CD44 variants and prognosis in oesophageal squamous cell carcinoma

The CD44 variant (CD44v) isoforms have been noted as markers for tumour metastasis and prognosis in several adenocarcinomas.

To investigate whether CD44v, especially the CD44v2 (v2) isoform, may be a useful prognostic factor for patients with oesophageal squamous cell carcinoma, using a recently developed monoclonal antibody against a v2 epitope.

233 patients (211 men and 22 women; mean age 61.9 years), with oesophageal squamous cell carcinomas curatively removed without additional treatment between 1987 and 1996 at the National Cancer Center Hospital, were analysed for CD44v expression.

The expression of CD44v was evaluated immunohistochemically using monoclonal antibodies against epitopes of the standard and variant protein, in paraffin embedded oesophageal squamous cell carcinoma tissue from 233 patients who had undergone cervical, mediastinal, and abdominal lymphadenectomy (three field dissection) for oesophagectomy. The data were evaluated for any correlation with clinicopathological indices or prognosis.

Although total CD44 and CD44v6 (v6) were respectively observed in 99% and 97% of the cancer specimens, the expression of v2 was only 30%. Patients whose tumours were v2 positive had a significantly better prognosis than those whose tumours were v2 negative (p = 0.031). Furthermore, in patients without lymph node metastasis, v2 positivity alone was a significant independent factor of prognosis (relative risk of death associated with v2 negativity, 4.7; p = 0.037) in multivariate analysis.

These results indicate that v2 is a useful marker for clinical prognosis in patients with oesophageal squamous cell carcinoma. Particularly in patients without lymph node metastasis, v2 status may thus have implications for the use of adjuvant chemotherapy and/or radiotherapy in patients with oesophageal cancer at an early stage.