Background and purpose: The expression of specific CD44 isoforms is associated with metastasis and poor prognosis in human malignant tumors. We retrospectively investigated the expression of the CD44 variant isoform v5 (CD44v5) in human renal cell carcinoma (RCC) specimens by immunohistochemistry.
Methods: We studied the expression of CD44v5 immunohistochemistry in archival tissue specimens from 72 RCC patients (47 men and 25 women) with a mean age of 60.1 years (range, 30 to 83 years) who underwent resection in our hospital from 1986 to 1996. The patients were divided into non-invasive (pT1, pT2, and pT3a; n = 49) and invasive groups (pT3b, pT3c, and any T with N+; n = 23). Among the 72 patients, 67 were followed for at least 60 months (up to 190 months) after radical nephrectomy. Twenty nine renal specimens, including 15 of normal renal parenchyma and 14 of inflammatory or immune renal diseases, were used as controls.
Results: All control group tissues expressed CD44v5. CD44v5 expression was detected in 66 of 72 RCC specimens (91.7%). In general, the expression of CD44v5 was higher in the non-invasive group [47/49 (95.9%) vs 19/23 (82.6%), p < 0.05]. Five cases were lost to follow-up. Thirty three of 67 patients (49.3%) died of RCC-related causes during the follow-up period. The CD44v5 non-expression group had a higher mortality rate than the expression group [4/5 (80%) vs 29/62 (46.8%), p < 0.001]. The 5-year and 10-year survival rates were significantly higher in patients with CD44v5 expression than in those without (p < 0.001).
Conclusions: This study found that CD44v5 expression was greater in early stage than in advanced stage RCC and was associated with tumor progression and long-term survival. Although the survival analysis showed both tumor stage and CD44v5 expression were significant prognostic factors in RCC, only tumor stage remained an independent factor.